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THIS  BOOK  MUST  NOT  BE  T, 
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EXPLOSIVES 


Digitized  by  the  Internet  Archive 

in  2010  with  funding  from 

NCSU  Libraries 


http://www.archive.org/details/explosives01mars 


J 


'     //    Mills.) 


EXPLOSIVES 


BY 

ARTHUR     MARSHALL 

A.C.G.I.,  F.I.C.,  F.C.S. 
Chemical  Inspector.   Indian  Ordnance  Department 

SECOND    EDITION 

Vol.   I 
HISTORY     AND     MANUFACTURE 


WITH  77  ILLUSTRATIONS 


PHILADELPHIA 

P.    BLAKISTON'S    SON    &   CO 


1012    WALNUT   STREET 
1917 


Printed  in   Great  Britain 


DEDI  e  AT  Et) 

!&v.  "permission 
Oo  trje  3\tg,l)t  Iftonourable 
DAVID     LLOg*D    GEORGE,    M/P. 

PRIME    MINISTER 

wr)0  during  tt>e  great    "(European  War  also  served 

r>is  llfing,  and    Country  as 

Chancellor  of  tr>e  TExcr>equer 

Mtinister  of  Mtunitions 

an6 

Secretary  of  State  for  ^Par 


'  Arma  Virumque  Cano  " 
Virgil. 


T1 

ft- 

4,\ 


- 


PREFACE  TO  SECOND  EDITION 

The  fact  that  a  second  edition  of  this  work  lias  been  called  for  only  a  year 
after  the  publication  of  the  first  indicates  that  it  was  really  wanted.  The 
Great  War  has  meantime  completed  the  second  year  of  its  course,  but  has 
not  caused  the  introduction  of  any  very  novel  explosives,  despite  sensational 
statements  of  some  journalists.  Certain  aspects  of  the  manufacture  of  ex- 
plosives have,  however,  become  of  greater  importance,  and  have  therefore 
been  treated  in  greater  detail  in  this  edition.  Picric  acid,  trinitrotoluene 
and  other  nitro-aromatic  compounds  were  formerly  merely  by-products  of 
the  dye  industry,  and  consequently  their  manufacture  seemed  only  to  call 
for  brief  notice  in  a  work  on  explosives.  Now,  however,  they  are  being  made 
on  a  very  large  scale  in  factories  specially  elected,  and  their  supply  has  become 
a  matter  of  national  importance  in  every  country  in  Europe.  Before  the  War 
nitric  acid  made  from  the  air  could  hardly  anywhere  compete  with  that  manu- 
factured from  sodium  nitrate,  but  the  blockade  of  Germany  has  altered  this. 
Thus  does  history  repeat  herself,  for  in  the  Napoleonic  wars  England  cut 
off  the  supply  of  potassium  nitrate  from  India  to  France  and  caused  a  great 
development  of  the  French  saltpetre  industry.  The  blockade  has  also  caused 
Germany  to  pay  more  attention  to  chlorate  and  perchlorate  explosives  and 
those  made  with  liquid  oxygen. 

The  publication  of  Les  Poudres  et  Ex])losifs,by  L.  Vennin  and  G.  Ches- 
neau,  has  enabled  me  to  improve  the  description  of  French  explosives  and 
methods.  As  in  the  first  edition,  but  little  space  has  been  given  to  explosive 
substances  that  have  not  any  commercial,  military  or  theoretical  impor- 
tance. A  systematic  account  of  all  classes  of  explosives,  organic  and  inorganic, 
Mill  be  found  in  the  work  of  Vennin  and  Chesneau  just  mentioned. 

I  have  spared  no  trouble  to  make  the  work  as  reliable  and  useful  as  pos- 
sible to  those  engaged  in  making  and  dealing  with  the  explosives  used  in  this 
titantic  struggle,  and  I  hope  that  in  this  way  I  have  assisted  slightly,  in  spite 
of  the  fact  that  I  am  detained  far  from  the  principal  theatres  of  war.  There 
are  of  course  some  matters  in  connexion  with  explosives  which  cannot  be 
published. 

My  best  thanks  are  given  to  my  former  fellow  student ,  G.  C.  Jones,  for  very 
kindly  undertaking  the  revision  of  the  proofs  and  the  preparation  of  the 
index,  thus  not  only  relieving  me  of  much  work,  but  also  greatly  expediting 
the  publication  of  this  edition.  My  former  colleague.  William  Barbour,  has 
made  a  number  of  useful  suggestions  and  supplied  me  with  copies  of  some 
naiiers  which  I  could  not  otherwise  have  obtained  in  time. 

A.  MARSHALL. 

Naini  Tal,  India. 
February,  1917. 


PREFACE  TO  FIRST  EDITION 

Sini  i:  the  late  Mr.  Oscar  Guttinann  published  his  work  on  the  Manufaeturt 
of  Explosives  in  ls!'~»  no  comprehensive  book  on  this  subject  has  appeared 
in  Rngtiflh.  In  the  interval  the  explosives  industry  has  undergone  many 
changes  :  every  branch  of  it  ha>  developed  enormously — even  that  of  black 
powder;  and  scientific  investigations  have  thrown  light  on  many  of  the 
problems  that  arise  in  the  manufacture  and  use  of  explosives.  Especially 
during  the  last  few  years  many  obscure  points  have  been  cleared  up.  It  i-^ 
hoped  therefore  that  the  presenl  work  will  be  found  to  supply  a  real  want. 

In  a  single  book  of  moderate  size  it  is  not  possible  to  treat  in  detail  every 
point  that  arises  in  connexion  with  explosives.  Consequently  it  has  been 
necessary  to  restrict  its  Bcope  in  some  directions.  The  methods  of  using 
explosives  belong  rather  to  the  subjects  of  ballistics,  blasting,  etc.,  and  their 
full  discussion  would  alone  require  a  larger  work  than  this.  Therefore  they 
have  only  been  referred  to  briefly.  Details  of  manufacture,  although  often 
of  much  practical  importance,  can  only  be  learnt  properly  in  the  factory  : 
consequently  they  have  been  omitted  in  many  cases.  Proposals  made  in 
patent  specifications  have  not  been  dealt  with  unless  they  possess  practical 
or  theoretical  importance  :  for  more  detailed  information  concerning  patents 
relating  to  explosives  the  reader  should  refer  to  works  such  as  those  of 
R.  Escales.  Subjects  which  are  treated  fully  in  the  ordinary  scientific  or 
technical  textbooks  have  only  been  dealt  with  in  bo  far  as  they  throw  new- 
light  on  problems  connected  with  explosiv*  3. 

On  the  other  hand,  an  endeavour  has  been  made  to  increase  the  usefulness 
of  the  book  by  collecting  allied  facts  from  scattered  BOurces,  and  placing  them 
in  juxtaposition  with  one  another.  Some  subjects,  which  are  only  mentioned 
briefly,  or  not  at  all,  in  other  hooks  have  been  treated  more  fully  than  their 
intrinsic  importance  would  otherwise  have  called  for.  Numerous  references 
to  original  papers,  etc.,  have  been  given  to  assisl  those  who  require  more 
detailed  information  concerning  the  subjects  dealt  with.  Considerable  Bpace 
has  been  given  to  matters  connected  with  the  difficult  and  intricate  question 
of  the  stability  of  uitro-cellulose  and  allied  compounds. 

I  am  indebted  fco  my  wife  for  her  valued  help  in  revising  the  book.  My 
thanks  are  also  due  to  Mr.  W.  Rintoul,  Mr.  J.  Thorburn,  and  Mr.  \V.  IJ.  Moore 
for  assistance  in  revising  the  proofs. 

It  i-  my  earnest  hope  that  the  book  may  he  of  help  to  my  country  in  the 
present  time  of  emergency. 

A.  MARSHALL. 

X  mm  Tal.  India. 


CONTENTS 

PAGE 

LIST  OF  PRINCIPAL  ABBREVIATIONS xv 

INTRODUCTION 

Explosion  :   Explosive  :  Gas    evolution    :    Heat     liberation  :    Sensitiveness 
Constituents  of  explosives  :  Oxygen  carriers  :  Combustible  constituents  : 
Xitro-aromatie  compounds  :  Nitric  esters  :  Smokeless   powders  :   En  lo- 
thermie    compounds  :   Velocity    of   explosion  :   Incomplete    detonation: 
Stability  :  Summary    ..........         1 


PART    I:     HISTORICAL 

CHAPTER  I 

EARLY  HISTORY 

Gunpowder  :  Confusion  of  terms  :  Incendiary  mixtures  :  Greek  fire  :  Wild- 
fire :  Saltpetre  :  The  Chinese  :  The  Indians  :  Roger  Bacon  :  The  Arabs  : 
Invention  of  fire-arms  :  Summary  :  Gibbon  .  .  .  .  .11 

CHAPTER  II 

DEVELOPMENT  OF  GUNPOWDER 

Early  manufacture  :  Early  powder-making  machinery  :  Incorporating  mil!  : 
Stamp  mills  :  Additions  to  gunpowder  :  Corned  powder  :  Pressed  powder: 
Breaking  down  :  Composition  of  gunpowder  :  Testing  gunpowder  :  Fire- 
arms :  Double-barrelled  guns  :  Rifles  :  Cannon  :  Projectiles  :  Incendiary 
missiles  :  Shell  :  Fuses  :  Hand-grenades  :  Infernal  machines  :  Fire- 
works :  Military    mines  :  Blasting  .  .  .  .  .  .  l'.'J 

CHAPTER  III 

PROGRESS  OF  EXPLOSIVES  IN  THE   EIGHTEENTH 
AX  I)  NINETEENTH  CENTURIES 

Berthollet,  Chlorate  :  Igniters  :  Forsyth's  detonator  lock  :  Fulminates  :  Caps  ; 
Fuses  :  Gun-cotton  :  Nitro-glycerine  :  Ammonium  nitrate  explosives: 
Sprengel  explosives  :  Coal-mine  dangers  :  Cheddite  :  Inspection  of 
explosives  :  Smokeless  powders  :  Picric  acid  :   Trotyl      ....       3S 


I ONTENTS 


PART   II:     BLACK    POWDER 

I  HAPTER    IV 

MANUFACTURE  OF  SALTPETRE 

Nitre  deposits      French  saltpetre  industry  :  Artificial  nitre    beds  :   EngKah 
Baltpetre  industry  :  Formation  of  nitrates  :  BertneJ 
terial  action  :  Indian  saltpetre  industry  :  Indian  refinery  :  Chili   nita 
deposits  :  "Conversion"  Baltpetre  :  Refining  saltpel         S  Itpetre  from 
the  atmosphere  ........... 

I  HAPTER  V 

MANUFACTURE  OF  <  EAR*  OAL  AND  SULPHUR 

(lian-oal  :  Wood  used  :  Distillation  Composition  :  Brown  charcoal: 
Sulphur  :  Sicilian  sulphur  :  By-product  sulphur  :  Louisiana  sulphur  : 
Refining  sulphur  :  Properties  :  Function-  of  sulphur      ....       67 

<  B  AFTER  VI 

MANUFACTURE  OF  GUNPOWDER 

Advantages   and   disadvantages   :    Composition  :  Grinding   the   ingrediente 
Weighing  and  mixing  :  Incorporating  or  milling  |    tnatic  drench 

oving  the  mill-cake  :  Breaking  down  :  Pressing  :  Granulating  or  corn- 
ing :  Dusting  and  glazing  :  Stovingor  drying  :  Finishing  and  blending: 
Cut   powders  :  Moulded  powders  :  Blasting  powders  :  Sprengsalpeter : 
Cahuecit  :  Petroklastit  :  Bobbinite  :  Water-soluble  powder  :    1 
of  explosion       ...........       "3 


PART    III:     ACIDS 
<  EAPTER  Vll 

SULPHURIC  A<  11> 

Manufacture  :  Purification  :  Concentration  :  Melting-points  :  Specific  gravi- 
ties :  Calculations  :  Supplies  in  war-time.        ...... 

CHAPTER  VIII 

NITRIC  ACID 

Manufacture  :  Recovery  of  nitron-  fumes  :  Storage  :  The  distillation  :  Xitre 
Nitric   acid  from  the  atmosphere  :  Direct  oxidation  mide 

pro.  :    rpek's  process  :   Haber's  pi  Ostwald's   pi 

perties  :   Specific   graviti*  ring-points  :    Boiling-points  :    vapour 

pressuree    ........-•••     1"' 


CONTENTS  xi 

r  \or. 

CHAPTER  IX 

MIXED  AND  WASTE  ACIDS.    MANIPULATION 

Mixed  acid  :  Mixing  the  acids  :  Properties  of  mixed  acids  :  Specific  gravities  : 
Vapour  pressures  :  Waste  acid  :  Gun-cotton  waste  acid  :  Nitro-glycerine 
waste  acid  :  Nitro-compound  waste  acid  :  Denitration  plant  :  Manipulation 
of  acids  :  Materials  :  Raising  acid  :  Oleum        .....     120 

PART   IV:     NITRIC   ESTERS   OF   CARBOHYDRATES 

CHAPTER  X 

THEORY  OF  NITRATION  OF  CELLULOSE 

Stages  of  nitration  of  cellulose  :  Highest  attainable  nitration  :  Solubility: 
Soluble  nitrocellulose  :  Quantity  of  acid  :  Consumption  of  acid  :  Effectof 
nitrous  acid  :  Temperature  and  time  of  nitration  :  Nature  of  the  cotton  : 
Nitro-cottons  of  low  nitration  :  Pyroxylin  :  Collodion   ....      135 

CHAPTER    XI 

CELLULOSE 

Nature  of  cellulose  :  Ligno-cellulose  :  Compound  celluloses  :  Reactions  of 
cellulose  :  With  sulphuric  acid  :  With  nitric  acid  :  Mercerized  cotton  : 
Viscose  :  Cellulose  benzoates  :  Acetates  :  Schweitzer's  reagent  :  Hydrate 
cellulose  :  Oxy-cellulose  :  Nitro-oxycellulose.  etc.  :  Viscosity  :  Over- 
bleached  cotton  :  Nitrated  mercerized  cotton  :  Effect  of  dilute  alkali  : 
Cotton  used  in  manufacture  :  Wood  cellulose  :  Action  of  bacteria  :  Struc- 
ture of  cotton  fibre  :  Dead  cotton        .  .  .  .  .  .  .148 

CHAPTER    XII 

MANUFACTURE  OF  NITROCELLULOSE     L^ 

Picking  the  cotton  :  Teasing  :  Drying  :  Nitrating  :  Abel's  process  :  Centrifugal 
process  :  Direct  dipping  :  Displacement  process  :  Hyatt  nitrator  :  High 
nitrogen  gun-cotton  :  Partially  soluble  nitro-cottons  :  Soluble  nitro- 
cottons  :  Pyrocollodion  :  Collodion  for  blasting  gelatine  :  Collodion  for 
other  purposes  .  .  .  .  .  .  .  .  .  .  .168 

CHAPTER  XIII 

THE  STABILIZATION   OF  NITRO-CELLULOSE 

Early  methods  :  Boiling  :  Pulping  :  Removal  of  foreign  bodies  :  Poaching  : 
Blending  :  Addition  of  calcium  carbonate  :  Mouldmg,  etc.  :  The  beater: 
Alkaline  method  of  stabilization  :  Sulphuric  esters  :  Velocity  of  hydrolysis 
of  nitro-cellulose  :  U.S.  Ordnance  method  ;  Cellulose  nitrites  :  Products 
of  decomposition  :  Washing  collodion  cotton         .....      182 


xii  I  I  >\T1-;.Y1  - 

PAGE 

I  EAPTEB  XIV 
NITRK    ESTERS  OF  OTHER  CARBOHYDRATES 

Nitro-starch  :  Xiti  .  .         .         .         .         ,         .194 

PART   V:     NITRIC    ESTERS   OF   GLYCERINE 

•  BARTER  XV 

QLY(  ERINE 

•  glycerin      S  -      Purification  of  spent  lye  :  Concentration: 

Autoclave  pi  ombined  process  :  Twite-hell  process     Ferment  pro- 

Distillation        .         .  .         .         .         .         .         .  i*i  l 

I  EAPTER    XVI 

MANDEACTDRE  <  »F  NTTRO-GLYCERINE 

Early  methods  :  Modern  plant  :  Nitrator  :  Injector  :  Separator  :    Prewash 
tank  :   Washing  :   Filtering  :   Wash-waters   :   After-separation  :   Recent 
improvements  :  Abolition  of  cocks  :  Fume   hoods    :    Plugs   for   air-holes  : 
ring  die  washing  waters  :  Washing  operate  Tinths  :  Nitrator- 

■  oling      coils    :    Prevention    of    after-separation    :    Drowning 
arrangement-  -  and  yields  :  Time  of  separation  :  Conveyani 

nitro-glyeerine  :  Gutters  :  Location  of  factory  :  Air-supply  :  Limit  boards  : 
Thundei  leral  precautions  :  Sensitiven*  -  .     2 

CHAPTER  XVII 

LOW -FREEZING   NITRO-GLYCERINE 

a  of  nitro-g  explosi  if  addition-  :  Super-cooling 

Dinitro-glycerine  :  Dinitro-chlorhydrin  :  Dinitro-acetin  :  Dinitro-formin  : 
Tetranitro-diglycerine  :   Dinitro-glycol    :   Nitro-isobutyl-glycerine  nitrate 


PART    VI:     NITRO-AROMATIC   COMPOUNDS 

<  BAPTER     Will 
BY-PRODU<  T8  OF  I  OAL  DISTILLATION 

Aromatic  compounds  :  Distillation  of  coal  :  Coal-tar:  Nomenclature  :  Benzol 

from  gas  :  Distillation  of  coal  tar  :  Toluene  from  petroleum  :  <  Sarbolic  acid  : 
Phenol  from  benzene  :  Naphthalene  :  Yields         .....     245 


CONTENTS 


xin 


CHAPTER  XIX 
NITRO-DERIVATIVES  OE  AROMATIC  HYDROCARBONS 
Nitre-benzene,  C6H5N02  :  Accidents  :  Dinitro-benzene,  C6H4(NO.,)o  ■  Trinitro- 
beirzene,  C6H3(N02)3  :  Nitro-tomene,  C7H7N02  :  Dinitro-toluene,  C7H0 
N204  :  Trnntro-toluene.  C7H5N306  :  Waste  acids  :  Purification  of 
trmitro-toluene  :  The  trinitro-toluenes  :  Accidents  :  Properties  :  Density  ■ 
Mono-nitro-naphthalene,  CJ0H7NO2  :  Dinitro-naphthalene,  Cl0H6NaO4 : 
Irmitro-naphthalenc,  C10H5N3Oc  :  Tctranitro-naphthalene,  C10H4N4O8    .     253 

CHAPTER  XX 
OTHER  NITRO-AROMATIC  COMPOUNDS 

Allili/p'wV1?5n^^I)ipheuylan,ilie'  (CeH^NH  :  Hexanitro-diphenylamine, 
[tl  S   r fi2  :   Nltr°-aillhlul«   :    Nitro-methylanilines    :    Manufacture 

ot  tetryl  :  I  roperties  of  tetryl  :  Higher  nitro-derivatives  of  methyl-aniline  : 
Picric j  acid,  C,H3N,07  :  Properties  :  Higher  nitrb-phenols  :  Styphnic  acid, 
C6H8N,03  :  Irmitro-cresoi,  C(;H.OH.CH3(N02)3  :  Picratea  and  trimtro- 
cresylates  :  Tnmtro-anisole,  C6H2OCH3(N02)3  :  Kinetics  of  nitration     .     272 


PART   VII:      SMOKELESS    POWDERS 

CHAPTER  XXI 

SLOW -BURNING  SMOKELESS  POWDERS 

Drying  the  nitro-cellulose  :  Alcoholizing  :  Incorporation  :  Shaping  the 
powder  :  Poudre  B  :  Russian  powder  :  Rumanian  powder  :  Belgian 
powder  :  American  powder  :  Spanish  powder  :  Ballistite  :  Filite  :  Solenite : 
German  powders  :  Cordite  :  Weighing  the  gun-cotton  :  Measuring  the 
nitro-glycerine  :  Mixing  :  Incorporating  :  Pressing  :  Drying  :  Japanese 
powder  :  Sporting  rifle  powders  :  Axite  :  Moddite       .         .         .         .289 

CHAPTER  XXII 

REQUIREMENTS  OF  A  SLOW-BURNING  SMOKELESS  POWDER 

Rate  of  burning  :  Form  of  powder  :  Progressive  powder  :  Erosion  :  Nitro-gly- 
cerine v.  nitro-cellulose  powders  :  Erosion  :  Backflash  :  Muzzle  flame  : 
Products  of  explosion  :  Testing  propellants  :  Efficiency       .  .  .310 

CHAPTER    XXIII 
FAST-BURNING  SMOKELESS  POWDERS 

Shot-gunpowders  :  Condensed  powders  :  Bulk  powders  :  Ingredients  •  Manu- 
facture of  bulk  powders  :  American  method  :  33-grain  powders  :  30 -grain 
powders   :    French    powders  :  German    powders  :  American    powders 
Austrian  powders  :  Requirements  :  Testing  shot-gun  powders  :   Powders 
for  trench  howitzers  :  Blank  powders        ...  .         .     322 


xiv  I  ONTENTS 

PAGE 

<  SAFTEB  XXIV 

SOLVENTS 

available  :  Ether  alcohol  :  Nature  of  colloid.-  :  Manufacture  of 
acetone  :  Permanganate  test  :  Impurities  :  Acetone  from  starch  :  Acetone 
from  acetylene  :  Recovery  of  ts  :  Acetone  recovery  :  Volatility  of 

nitro-glvcerine  :  Yapou:  deity  of  vapours      .  .  .     336 

PART    VIII:     BLASTING    EXPLOSIVES 

I  BAPTEE  XXV 

NTTRO-GLY*  BRINE  HIGH  EXPLOSIVES 

1\  •  lguhr  :  Manufacture  of  dynamite  :  Properties  of  dynamite  :  French 
dynamites  :  American  dynamite  :  Ligdvn  :  Ammonia  dynamite  :  Judson 
powder  :  Dynamite  Xos.  2  and  3  :  Gelatinized  e>  •  >r  jelly  : 

Diminution  of  sensitiveness  and  stability  :  Gelignite  :  Gelatine  dynamite  : 
Wrapper-  4'  pel  cent,  dynamite  :  American  gelatin  dynamites  :  Forcite  : 
French  gelatinized  exi  Low-freezing  explosr.  ■       v   : 

containing  nitro-glycerine  :  Carboi  ...... 

<  HAPTKI:   XXVI 

I  ELORATE  EXPLOSIVES 

Chlorate  dangers  :  Sprengel  explosive -  :  Promethee  or  <  »3  ;  Rack-a-rock  : 
Cheddite  :  Steelite  :  Silesia  :  Potassium  perchlorate  ex  Permonite  : 

Alkalsite  :  Polarite  :  M.B.  powder  :  Ammonium  perchlorate  exi 
Yonckite  :  Blastine   ..........      :;TT 

CHAPTER  XXVII 
AMMONIUM  NITRATE  EXPLOSIVES 

Favier  expl<  -      -      I  -risounites  :  Ammonals  :  Sabulite  :  Grisoutine      .  .     3SS 

Ihdkz  of  Names     ...........     399 

Lndex  of  Subjl  ....  .....     402 


LIST  OF  PRINCIPAL   ABBREVIATIONS 


A.  and  E. 

Aug. 

AM. 

Ber. 

Bull. 

Ghem.   Ind. 

Chan.  Trade. 

Co?npt.  Bend. 

C.Z. 

J.  Soc.  Chem 

Ind. 
P.  ct  S. 
Phil.  Trans. 
Proc.  B.S. 
S.B. 

s.s. 

Trans.  Chem. 
Soc. 


JOURNALS,  ETC. 

Arms  and  Explosives. 

Zeitschrift  fur  angewandte  Chemie. 

Annual  Reports  of  II. M.   Inspectors  of  Explosives. 

Berichte  of  the  German  Chemical  Society. 

Bulletin  of  U.S.  Bureau  of  Mines. 

Die  chemische  Industrie. 
J.  Chemical  Trade  Journal. 

Comptes  Rendu*. 

('In  tnilu  r-Zeitung. 
.    Journal  of  the  Society  of  Chemical  Industry. 

Memorial  des  Poudres  ct  Salpetres. 
Philosophical  Transactions  of  the  Royal  Society. 
Proceeding*  of  the  Royal  Society. 
Special  Reports  of  H.M.  Inspectors  of  Explosives. 
Zeitschrift  fur  da*  gesamte  Schies-  und  Sprengstofj 
Transactions  of  the  Chemical  Society. 


Chalon. 
Cundill  and 

Thomson. 
Hime. 

Manufacture. 
Monumaita. 
Twenty  Years' 

Progress. 
Rise  and 

Progress. 
YVorden. 
Zschokke. 
Vennin  and 

Chesneau. 


BOOKS 
Li  *  Explosifs  Modernes. 

Dictionary  of  Explosiv 

Gunpowder  and  Ammunition,  by  Lieut. -Colonel   Hime. 
The  Manufacture  of  Explosives,  by  ().  Guttmann. 
Monumenta  Pulveris  Pyrii,  by  O.  Guttmann. 
Twenty   Years'  Progress  in  Explosives,  by  O.  Guttmann. 

The  Rise  and  Progress  of  the  British  Explosive*  Industry. 

The  Xitro-cellulosc  Industry,  by  Worden. 
Militarisclic  Spengtecknik,  by  B.  Zschokke. 
Les  Poudres  et  Explosifs,  1914. 


OTHER  ABBREVIATIONS 

b-P-  I  )ui  ling-point.  G/c.  guncotton. 

c-c-  cubic  centimetres.  m.p.  melting-point, 

coll.  cot.  collodion  cotton.  X   .  .  nitro-celluloE 

D/n/g-  dinitroglycerine.  N/g.  nitro-glycerine. 

D/n/t.  dinitrotoluene.  sp.  gr.  specific  gravity. 

S-  grammes.  T/n/t.  trinitrotoluene. 

Temperatures  are  always  in  d<  ntigrade  unless  otherwise  stated. 


INTRODUCTION 

Explosion  :  Explosive  :  Gas  Evolution  :  Heat  Liberation  :  Sensitiveness  :  Con- 
stituents of  Explosives  :  Oxygen  Carriers  :  Combustible  Constituents  :  Nitro- 
aromatic  Compounds  :  Nitric  Esters  :  Smokeless  Powders  :  Endothermic  Com- 
pounds :  Volocity  of  Explosion  :  Incomplete  Detonation  :  Stability  :  Summary 

When  gas  or  vapour  is  released  so  suddenly  as  to  cause  a  loud  noise  an  Ex  IosiOD 
explosion  is  said  to  occur,  as,  for  instance,  the  explosion  of  a  steam  boiler  or  ^ 
a  cylinder  of  compressed  gas.  Great  and  increasing  use  is  made  of  explosive 
processes  in  gas,  petrol,  and  oil  engines  for  driving  machinery  of  all  kinds. 
In  these  engines  the  material  that  explodes  is  a  mixture  of  air  with  com- 
bustible gas,  vapour,  or  finely-comminuted  liquid,  and  in  the  explosion  these 
are  suddenly  converted  into  water  vapour  and  the  oxides  of  carbon,  which 
latter  arc  gases.  Although  all  these  things  arc  liable  to  explode,  none  of 
them  arc  called  explosives  ;  this  term  is  confined  to  liquid  and  solid  sub- 
stances, which  produce  much  more  violent  effects  than  exploding  gasoous 
mixtures,  because  they  occupy  much  smaller  volumes  originally. 

An  explosive  is  a  solid  or  liquid  substance  or  mixture  of  substances  which  Explosive, 
is  liable,  on  the  application  of  heat  or  a  blow  to  a  small  portion  of  the  mass. 
to  be  converted  in  a  very  short    interval    of    time    into    other   more   stable 
substances  largely  or  entirely  gaseous.     A  considerable  amount   of  heat   is 
also  invariably  evolved,  and  consequently  there  is  a  flame. 

That  evolution  of  gas  (or  vapour)  is  essential  in  an  explosion  is  rendered  Gas  Evolu- 
cvident  by  considering  thermit.  This  consists  of  a  mixture  of  a  metallic  "on. 
oxide,  generally  oxide  of  iron,  with  aluminium  powder.  When  suitably 
ignited  the  aluminium  is  converted  into  oxide  and  the  iron  or  other  metal 
is  set  free  in  a  short  interval  of  time  with  the  evolution  of  an  enormous  quantity 
of  heat,  but  there  is  no  explosion.  It  is  indeed  because  no  gas  is  evolved 
that  thermit  can  be  used,  as  it  is,  for  local  heating  and  welding. 

It  is  also  an  essential  condition  that  heat  should  be  evolved  in  an  explosive  HeatLibera- 
reaction,  otherwise  the  absorption  of  energy  due  to  the  work  done  by  the  tion- 
explosion  would  cool  the  explosive  and  consequently  slow  down  the  reaction 
until  it  ceased,  unless  heat  were  supplied  from   without.     Ammonium  car- 
bonate, for  instance,  readily  decomposes  into  carbon  dioxide,  ammonia,  and 
vol.  i.  l  j 


WmZTY  LIBRARY 
DLIlSUmCmU*** 


[NTRODU*  HON 


Sensitiveness. 


Constituents 
of  Explosives. 


water,  but  in  bo  doing  it  absorbs  heal  ;  consequently  the  reaction  is  much  too 
-low  to  be  explosive.  Ammonium  nitrate,  on  the  other  hand,  is  decomposed 
into  oxygen,  nitrogen,  and  water,  with  the  evolution  of  heat,  and  i<  con- 
sequently liable  to  explode.  A  violent  impulse  is  required  to  start  the 
explosion,  but  nine  it  i~  Btarted  the  energy  (or  heat)  liberated  Buffices  to 
propagate  the  explosion,  unless  the  conditions  be  such  that  the  energy  is 
dissipated  mure  rapidly  than  it  is  liberated. 

Another  essentia]  for  an  explosive  i-  that  the  reaction  shall  not  set  in 
until  an  impulse  i-  applied.  If  the  reaction  sel  in  spontaneously,  it  is  obvious 
that  its  energy  cannot  be  utilized  in  the  form  of  an  explosion.  A  mixture 
<.f  sodium  and  water  evolve-  hydrogen  with  the  liberation  of  heat,  hut  reaction 
in  immediately  the  two  substances  come  in  contact  with  one  another. 
Different  explosives  require  impulses  of  very  different  strengths  to  cause 
them  to  explode.  Some,  such  as  diazobenzene  nitrate,  are  exploded  by 
a  slight  touch:  these  explosives  are  of  no  practical  utility  as  they  are  too 
unsafe.  Others,  Buch  as  fulminate  of  mercury,  are  exploded  by  a  moderate 
blow  or  a  small  flame  ;  these  are  used  principally  for  charging  caps  and 
detonators,  a  Bmall  quantity  serving  to  explode  a  large  amount  of  some  other 
I —  sensitive  explosive.  Most  of  the  explosives  now  used  can  be  exploded 
by  a  blow  only  if  it  be  extremely  violent,  and  many  of  them  cannot  be 
exploded  by  aflame  in  the  open  in  ordinary  circumstances.  The  tendency  is 
to  use  less  sensitive  explosives  because  they  are  safer  to  handle,  but  it  should 
never  be  forgotten  that  the  term  "  safe,"  when  applied  to  an  explosive,  is 
only  a  comparative  one.  The  duty  of  an  explosive  is  to  explode,  and  if  it 
i  not  treated  with  proper  respect  it  will,  sooner  or  later,  explode  at  the  wrong 
time  with  extremely  unpleasant  results. 

Before  the  subject  of  explosives  was  understood  so  well  as  it  i-  now, 
inventor-  were  very  liable  to  think  an  explosive  was  very  powerful,  and  there- 
fore valuable  merely  because  it  was  very  sensitive,  whereas  too  great  a  degree 
of  sensitiveness  is  really  a  most  <  bjectionable  feature.  In  the  middle  of 
the  nineteenth  century  many  such  mixture-  as  potassium  chlorate  and  picric 
acid  were  proposed  through  this  want  of  comprehension  of  a  fundamental 
condition. 

The  explosive  gaseous  mixtures  used  in  gas  and  oil  engines  to  which  refer- 
ence has  been  made  are  composed  of  a  combustible  material,  consisting  largely 
of  carbon  and  hydrogen,  and  air,  the  useful  constituent  of  which  is  oxygen. 
Similarly,  nearly  all  commercial  explosives  are  composed  partly  of  combustible 
element-,  of  which  carbon  and  hydrogen  are  the  most  important,  and  partly 
of  oxygen  combined,  but  not  directly  with  the  hydrogen  and  carbon.  <  >n 
explosion  the  oxygei  combines  with  the  hydrogen  to  form  water,  and  with 
the  carbon  to  form  carbon  monoxide  or  dioxide,  or  a  mixture  of  the  two. 
It  i-  the  heat   -et   free  in  tin-  com tm-t ion  that  i-  the  main  or  entire  cause  of 


INTRODUCTION  3 

the  rise  of  temperature.  The  formation  of  these  two  oxides  of  carbon  liberates 
very  different  quantities  of  heat ;  12  grammes  of  carbon  unite  with  16 
grammes  of  oxygen  to  form  28  grammes  of  carbon  monoxide  with  the  libera- 
tion of  29  large  Calories,  and  the  same  quantity  of  carbon  unites  with  32 
grammes  of  oxygen  with  the  liberation  of  97  large  Calories. 

Consequently  an  explosive  is  considerably  more  efficient  if  it  contains 
sufficient  oxygen  to  oxidize  the  carbon  entirely  to  dioxide,  but  the  effect  is 
reduced  to  some  extent  by  the  relatively  high  specific  heat  of  carbon  dioxide. 
In  some  classes  of  explosives,  however,  a  very  high  temperature  is  objec- 
tionable ;  this  is  the  case  with  smokeless  powders  and  explosives  for  use  in 
coal  mines.  Smokeless  powders,  therefore,  are  generally  made  of  such  a 
composition  that  the  greater  part  of  the  carbon  is  oxidized  only  to  monoxide. 
But  there  is  always  some  carbon  dioxide  formed,  for  it  takes  up  some  of  the 
oxygen  from  the  water  vapour  and  liberates  hydrogen,  or  if  the  total  quantity 
of  oxygen  be  very  small  there  may  even  be  free  carbon  produced.  In  the 
case  of  safety  explosives  for  coal  mines,  the  temperature  of  explosion  is  also 
sometimes  kept  low  by  restricting  the  proportion  of  oxygen,  but  this  means 
is  not  free  from  objection  because  carbon  monoxide  is  poisonous.  Other 
methods  are  therefore  adopted  in  some  safety  explosives  to  reduce  the 
temperature. 

The  oxygen  may  either  be  contained  in  a  separate  compound,  such  as  oxygen 
saltpetre,  which  is  mixed  mechanically  with  the  combustible  material,  or  Carriers, 
the  two  may  be  combined  together  in  a  single  compound,  as  is  the  case  with 
nitro-glycerine,  trotyl,  and  many  other  modern  explosives.  The  substances 
rich  in  oxygen  are  often  referred  to  as  "  oxygen  carriers  "  ;  those  most  used 
are  nitrates,  chlorates,  and  perchlorates,  in  which  the  oxygen  is  united  to 
nitrogen  and  chlorine  respectively.  Ordinary  gunpowder,  or  "  black  powder," 
belongs  to  the  class  of  explosives  that  have  separate  oxygen  carriers,  in  this 
case  saltpetre.  The  table  on  page  4  shows  the  properties  of  the  principal 
oxygen  carriers. 

It  will  be  seen  from  this  table  that  the  proportion  of  available  oxygen  is 
about  the  same  in  the  chlorates  as  in  the  corresponding  nitrates,  but  whereas 
the  chlorates  decompose  with  the  evolution  of  a  small  amount  of  heat,  the 
nitrates  require  a  considerable  amount  of  heat  to  split  them  up,  except  in  the 
case  of  the  ammonium  compound.  Explosives  containing  chlorates  are  con- 
sequently much  more  powerful  than  those  containing  nitrates,  but  they  are  also 
very  sensitive  unless  special  measures  are  adopted  to  render  them  more  inert. 
The  perchlorates  require  considerably  less  heat  to  decompose  them  than 
the  nitrates,  and  have  more  available  oxygen.  As  they  are  now  produced 
at  quite  low  cost  by  electrolytic  methods,  it  is  not  surprising  to  find  that 
they  are  being  used  more  and  more  for  the  manufacture  of  explosives.  Ammo- 
nium nitrate  and  perchlorate  decompose   with    the   evolution   of   heat,  this 


4  [NTRODUCTION 

being  due  to  the  formation  of  water,  but  the  available  oxygen  i>  diminished 
by  the  Bame  cause.  Ammonium  nitrate  can  lie  detonated  by  itself ,  although 
<>nlv  with  difficulty,  and  then  <_rive>  a  Large  volume  of  :_ra-  at  a  comparatively 
l«»w  temperature.  In  consequence  of  this  low  temperature  it  has  been  found 
verv  useful     -  ostituent  of  safety  explosives  for  use  in  coal  mine-,  hut 

it  also  forms  pari  of  many  other  high  explosives.  Ammonium  porchlorate 
Buffers  under  the  disadvantage  that   amongst   it>  products  losion  is 

the  poisonous  Lra-.  hydrogen  chloride,  or  hydrochloric  acid. 


( >\  .  1 
carrier 

Molecular 
wi  ighl 

Heat  evolved 

gen    avail 
able 

per 
mol. 

erams. 

per 

grams. 

I0Q 

A'  U  ■ 

Potassium. 

101*1 

2-08 

2KN0       KtO  +  N    - 

3     - 

82 

-    lium 

BS 

2-26 

_'\    V  I       NasO+N, 

■ 

—  71-3 

47 

•iuin 

K.4-1 

_ 

'                '                5 

- 

115 

Barium 

261-5 

- 

B     NO    ,     BaO  +  N 

31 

a 

Lead     . 

11-1 

4-58 

SO    '     J''.o-n"- 

' 

" 

. 

in 

Ammonium 

Bl  -1 

1-71 

NH4NO      2H,O+Nt+0 

-' 

■ 

_ 

34 

Chlorates. 

in. 

122-6 

2-00 

K<  10       K( 

+  11-9 

3 

7^ 

B   lium 

106-5 

NaCIO       N 

-  13-1 

-  12-3 

4.". 

11":; 

Barium 

304-3 

- 

lO^B.  1 

2J 

8 

■ 

LOO 

Pcrchloi 

Potassium . 

138 

2-54 

KC104=KCl  +  40 

7'8 

117 

3    lium 

122-5 

— 

N  C104=NoCl  +  40 

-12-4 

-10-2 

52 

— 

Barium 

336-3 

— 

,04),  =  BrX"L  +  80 

4-3 

-    1-3 

38 

— 

Ammonium 

IT-.". 

1-89 

2NH4C10       -         -::H.O 

- 

25 

Potassium  permanganate  and  bichromate  have      -         en  used,  but  they 
wees  i      -       ial  advai      _  Permanganate  explosiv  often  incon- 

veniently sensitive.     Attempts  have  also  been  made  to  use  liquid  oxyg 
whi.h  has  the  advantage  of  being  cheap  and  containing  l  cnt.  of  avail- 

able oxygen,  hut  the  difficulties  of  employing  a    liquid  which   boils  at    2 
C.  below  the  ordinary  temperature      e  e     _      t  that  thesi 
given  up.     The  Germans  are,  however,  making  great  efforts  to  develop  tJ    - 
explosives  for  work  in  mine-    a       a  to  set  tree  [responding  quantity  of 

nitrates  for  military  use.     For  the  same  man  authorities  are 

encouraging  the  use  of  chlorates  and  perchloral 


INTRODUCTION  5 

In  black  powder  the  combustibles  are  charcoal  and  sulphur  ;  in  blasting  Combustible 
explosives  many  sorts  of  organic  matter  have  been  used  or  proposed,  and  Constituents- 
some  inorganic  substances,  such  as  potassium  ferrocyanide,  ammonium 
oxalate,  and  antimony  sulphide,  but  those  in  common  use  are  not  very  numer- 
ous. For  explosives  containing  nitroglycerin  an  absorbent  material  must  be 
used,  and  of  these  wood  meal  is  the  most  usual,  but  flour  and  starch  are  con- 
stituents of  some  nitro-glycerine  explosives,  and  in  a  few  cases  such  substances 
as  tan  meal  and  prepared  horse-dung  are  present.  Cork  charcoal  has  great 
absorptive  power,  but  its  high  cost  prevents  its  use.  Ordinary  charcoal 
is  a  constituent  of  some  explosives,  as  also  is  coal-dust.  American  dynamites 
often  contain  resin  and  sulphur,  and  these  constituents  are  sometimes  met 
with  in  other  explosives.  Oily  materials,  such  as  castor  oil,  vaselin,  and 
paraffin  wax,  reduce  the  sensitiveness  of  an  explosive,  and  one  or  other  of 
them  may  usually  be  found  in  a  chlorate  blasting  explosive.  The  addition 
of  aluminium  greatly  increases  the  heat  of  explosion  ;  it  is  present  in  the 
explosives  of  the  ammonal  type. 

Modern  high  explosives  very  frequently  contain  nitro-derivatives  of  the  Nitro-aro- 
aromatic  compounds  obtained  from  coal  tar,  especially  the  mono-  di-  and  matic-Com- 
tri-nitro-derivatives  of  benzene,  toluene,  and  naphthalene.  The  nitro-groups 
in  these  compounds  contribute  oxygen  for  the  explosive  reaction.  The 
trinitro-compounds  of  substances  containing  only  one  benzene  ring  are 
explosives  in  themselves  ;  trinitrotoluene,  for  instance.  Trinitrotoluene  is 
not  only  a  constituent  of  composite  explosives,  but  is  also  very  largely  used 
by  itself  as  a  charge  for  shell  and  submarine  mines,  and  for  other  military 
and  naval  purposes,  for  which  its  insensitiveness  combined  with  its  great 
violence  render  it  suitable.  Picric  acid  (trinitrophenol)  is  also  much  used 
for  these  purposes,  and  trinitrocresol  to  a  less  extent.  Although  they  deton- 
ate with  great  violence,  these  trinitro-compounds  do  not  contain  sufficient 
oxygen  to  oxidize  the  whole  of  the  carbon  they  contain  even  to  the  stage 
of  carbon  monoxide.  Their  power  as  explosives  is,  therefore,  increased 
by  mixing  them  with  oxygen  carriers.  Commercial  explosives  coBtaining 
trinitrotoluene  always  have  also  some  other  constituent  which  can  supply 
the  deficient  oxygen. 

Nitro-glycerine  and  the  nitro-celluloses  are  the  principal  members  of  Nitric  Esters, 
another  very  important  group  of  substances  that  can  be  used  as  explosives 
without  admixture.  Strictly  speaking,  they  are  not  nit ro-derivatives.  I.ui 
nitric  esters.  The  more  highly  nitrated  celluloses,  such  as  gun  cotton,  contain 
enough  oxygen  to  convert  all  the  hydrogen  into  water  and  the  carbon  into 
monoxide,  and  even  some  of  it  into  dioxide.  Nitro-glycerine,  C3H5X309,  not 
only  has  enough  to  oxidize  entirely  all  its  hydrogen  and  carbon,  but  also 
has  a  little  oxygen  left  over.  Nitro-glycerine  is  the  most  powerful  explosive 
compound  known,  but  its  power  is  increased  by  dissolving  in  it  a  small  pro- 


6  INTRODUCTION 

portion  of  nitro-celluk»e.  which  utilizes  the  excess  of  oxygen  and  at  the  samS 
time  converts  it  into  a  gelatinous  solid  known  as  Maying  gelatin. 

All  smokeless  powders  < "ii-i>t  largely  of  nitrocellulose,  which  has  been 
more  or  less  gelatinized  and  converted  into  a  compact  colloid  by  means  of 
a  suitable  solvent  ;  many  of  them  contain  practically  nothing  else,  but  in 
others  there  is  a  considerable  proportion  of  nitro-glveerine.  Small  percent* 
ages  of  mineral  jelly,  inorganic  nitrates,  and  other  substances  are  also  added, 
in  many  cases  to  improve  the  ballistics  or  the  stability.  Powders  for  rifled 
arms  are  always  colloided  as  completely  as  possible,  whether  they  be  for 
small-arms  or  ordnance,  to  make  them  burn  slowly  and  regularly,  but 
in  shot-gun  powders  the  original  structure  of  the  nitro-celluln-e  is  not 
always  destroyed  entirely,  as  they  are  required  to  burn  comparatively 
rapidly. 

There  are  some  explosive  compounds  winch  do  not  depend  for  their  action 
on  oxidation  or  reduction.  These  are  endothermic  substances,  which  decom 
pose  with  the  evolution  of  gas  and  heat  :  they  are  usually  rather  sensitive. 
The  only  compounds  of  this  class  that  are  of  commercial  importance  are 
fulminate  of  mercury.  Hgi('XO),,  and  lead  azide.  PbN«,  both  of  which  are 
■  inly  for  exploding  other  explosives. 

There  are  other  endothermic  explosive  compounds  in  which  the  heat 
liberated  on  decomposing  into  their  elements  is  only  of  minor  importance 
compared  with  the  larger  amount  set  free  by  the  redistribution  of  the  oxygen. 
Such  are  tetryl  and  mono-  and  dinitro-naphthalene. 

The  heat  and  gas  evolved  are  the  two  principal  factors  which  govern  the 
power  of  an  explosive,  i.e.  the  amount  of  work  it  can  do  in  the  way  of 
displacing  objects.  But  the  time  taken  by  the  explosion  is  also  a  matter  of 
great  importance.  The  rate  of  explosion  is  measured  by  making  a  column 
of  the  explosive,  confining  it,  if  necessary,  in  a  metal  tube,  and  measuring 
the  time  that  the  explosive  wave  takes  to  travel  a  known  distance.  In  black 
powder  and  similar  nitrate  mixtures  the  velocity  of  explosion  is  only  a  few 
hundred  metres  a  second,  but  with  modern  high  explosive-  the  velocity  of 
detonation  is  from  two  to  seven  thousand  metres  a  Becond.  This  naturally 
makes  them  much  more  violent  and  destructive.  Explosives  of  the  gunpowder 
type  are  used  when  earth  <>r  -« .ft  rock  is  to  be  blasted,  or  when  the  material 
must  not  be  broken  up  too  much.  Propellants  for  use  in  firearms  are  required 
t'>  burn  >l<i\\ly  :  for  rifled  arms  they  must  lie  .-lower  even  than  gunpowder. 
They  are  not  exploded  by  means  of  another  high  explosive,  but  merely  lit 
by  a  powerful  flame,  and  should  then  burn  by  concentric  layers.  The  rate  of 
burning  increases  with  the  pressure  in  the  gun,  but  for  completely  gelatinized 
powder-  it  i-  less  than  a  metre  a  second. 

The  more  insensitive  explosives,  Buch  as  trinitrotoluene,  if  tired  with 
a  weak  detonator  are  only  partially  decomposed.      Not  only  i.-  Borne  of  the 


INTRODUCTION  1 

explosive  merely  scattered,  but  the  velocity  of  the  explosive  wave  is  low. 
Consequently  the  effect  produced  is  comparatively  small. 

Another  important  property  of  an  explosive  is  its  stability.  It  should  stability, 
retain  its  properties  and  composition  unchanged  when  stored  even  for  a 
long  period.  Above  all  it  should  not  be  liable  to  explode  or  ignite  spon- 
taneously. Nitro-cellulose  unfortunately  is  liable  to  this  defect,  and  conse- 
quently special  precautions  have  to  be  taken  in  the  case  of  smokeless  powders 
and  other  explosives  containing  it. 

The  most  important  properties  of  explosives  are  :  power,  sensitiveness.  Summary, 
velocity  of  explosion,  stability  and  temperature  of  explosion.  The  power 
depends  upon  the  temperature  of  explosion  and  the  quantity  of  gas  and 
vapour  evolved.  The  prices  of  the  constituents  and  the  ease  and  safety  of 
manufacture  are  also  of  importance.  All  these  factors  are  dependent  on  the 
composition  of  the  explosive  and  some  of  them  on  its  physical  state. 


PART  I 

HISTORICAL 


CHAPTER  I 
EARLY   HISTORY 

Gunpowder  :  Confusion  of  terms  :  Incendiary  mixtures  :  Greek  fire  :  Wild-fire  : 

Saltpetre  :   The  Chinese  :  The  Indians  :  Friar  Bacon  :  The  Arabs  :  Invention  of 

firearms  :  Summary   :   Gibbon 

Since  the  very  earliest  times  man  has  been  searching  for  more  and  more  Gunpowder 
effective  means  of  killing  his  fellows  and  the  beasts  and  birds  that  threatened 
his  safety  or  provided  his  food  or  clothing,  but  there  is  reason  to  believe  that 
the  first  explosive,  gunpowder,  was  not  known  before  the  thirteenth  century. 
This  is  a  mixture  of  three  substances,  saltpetre,  sulphur  and  charcoal,  two 
of  which  have  been  known  from  time  immemorial,  for  sulphur  occurs  native 
in  a  state  of  considerable  purity  in  some  volcanic  districts,  and  charcoal  is 
made  by  simply  heating  wood.  The  early  history  of  gunpowder  and 
explosives  generally  is  therefore  closely  connected  with  the  discovery  of 
methods  of  preparing  and  purifying  saltpetre. 

The  investigation  of  this  and  other  similar  matters  is  rendered  difficult  Confusion  of 
not  only  by  the  scarcity  of  early  records,  but  also  by  the  great  uncertainty  term8, 
as  to  their  true  interpretation.  When  saltpetre,  gunpowder  and  guns  were 
discovered  or  invented,  new  words  were  not  made,  but  old  terms  were  adopted 
which  had  previously  been  used  for  somewhat  similar  objects.  Our  word 
"powder,"  for  instance,  means  any  dust-like  material,  but  the  term  smokeless 
powder  is  now  used  to  denote  a  class  of  substances  which  have  nothing  in 
common  with  dust.  "  Gun  "  is  from  the  old  English  "  gonne,"  which  was 
used  to  denote  an  instrument  for  throwing  projectiles  before  the  introduction 
of  gunpowder.  Similarly  the  Arabic  "  bunduq  "  (ij^Jcj)  now  used  for  any 
rifle  or  sporting  gun,  formerly  meant  a  pellet  shot  from  a  small  catapult  used 
for  sporting  purposes.  Saltpetre  (sal  petra?)  merely  means  salt  of  the  rock, 
and  the  other  Latin  term  for  the  same  material,  "  nitrum  "  (nitron,  nitre), 
formerly  meant  soda  or  any  other  white  efflorescence.  Both  nitron  and 
natron  in  late  Latin  were  derived  from  the  Arabic  ^y^  (Ntruu),  some  of 
the  vowels  being  usually  omitted  in  writing  that  language  as  in  shorthand. 
Similar  difficulties  occur  with  the  terms  in  other  languages.  Nevertheless, 
considerable  progress  has  lately  Jbeen  made  in  ascertaining  the  early  history 
of  gunpowder  and  fire-arms,  and   various  wild  statements  as  to  the  great 

ll 


i2  EXPLOSIVES 

antiquity  <>f  the  knowledge  of  gunpowder  in  some  countries  are  now  quite 
discredited,  as  it  is  found  that  t lit-  evidence  upon  which  tl  -  statements 
were  made  will  not  bear  scrutiny. 

Long  before  the  discovery  of  saltpetre,  incendiary  materials  had  been 
used  in  warfare,  such  as  pitch,  Bulphur,  petroleum  and  other  oils.  Burning 
brands  were  frequently  attached  to  arrows  or  were  thrown  by  means  of  engines 
(catapults),  and  the  descriptions  of  the  effects  produced  by  these  early  "  fire- 
arms" is  often  so  fanciful  and  ggerated  that  they  have  been  thought 
to  imply  the  use  oi  gunpowder,  with  which  they  really  have  no  connexion. 
A  hall  of  burning  pitch  mixed  with  Bulphur  and  naphtha  thrown  against 
a  wooden  building  or  ship  would  cause  a  lire,  which  if  not  quickly  extin- 
guished might  prove  disastrous.  Such  incendiary  mixtures  were  known 
in  England  a-  "  wild-fire."  The  prompt  application  of  a  bucket  of  water 
or  some  sand  would,  however,  remove  the  danger.  Heme,  although  iso) 
instances  occur  in  ancient  history  where  great  success  was  achieved  with 
these  incendiary  mixtures,   they  must   generally   have  proved  ineffective. 

The  one  notable  exception  to  this  is  the  "Greek-fire"  or  "sea-fire," 
the  secret  of  which  prevented  the  conquest  of  Constantinople  and  Europe 
by  the  Moslem-,  for  several  centuries.  About  the  year  a. p.  668,  some  forty- 
six  years  after  the  flight  of  Mohamed  from  .Mecca  to  Medina,  the  Aral'-,  still 
at  the  height  of  their  conquering  enthusiasm,  commenced  to  beleaguer  Con- 
stantinople by  land  and  sea.  when  an  architect  named  Kallinikos  tied  from 
Heliopolis  in  Syria  to  the  Imperial  city  and  imparted  the  secret  of  the  " 
fire."  This  repeatedly  spread  such  terror  and  destitution  among  the  Moslem 
fleet,  that  it  was  the  principal  cause  of  the  siege  being  eventually  raised  after 
•l  years.  In  a.d.  716  to  718,  the  Arabs  again  appeared  before  Constanti- 
nople with  eighteen  hundred  ships,  hut  again  were  defeated  by  the  I 
BO  effectually,  that  after  a  stormy  passage  only  live  galleys  re-entered  the 
port  of  Alexandria  to  relate  the  tale  of  their  various  and  almost  incredible 
disast 

Russian  naval  forces  were  similarly  defeated  in  !»41  and  1043,  and  the 
Pisans  at    the  end   of  the  eleventh   century. 

What.  then,  was  the  nature  of  this  "sea-fire"  \  From  the  contemporary 
accounts  we  know  that  it  was  discharged  from  tubes  or  siphons  in  the  bows 
of  the  shi|i>.  l.ut  its  mode  of  preparation  was  kept  a  el.  I  and  it  was 

never  used  successfully  by  any  but  the  Greek  rulers  of  Byzantium.  There 
appears  to  he  no  doubt  that  naphtha  was  the  principal  ingredient,  and  it 
may  also  have  contained  sulphur  and  pitch.  Colonel  H.  W.  L.  fiime  came 
to  the  conclusion  that  it  must  have  Keen  mixed  with  quicklime,  the  slaking 
of  which  by  the  sea-water  raised  the  temperature  to  the  ignition  point  of 
the  sulphur.1  I  have  made  a  number  <»f  attempts  to  produce  ignition  in  this 
1  Ounpowder  ami  Ammunition.   London,   1904. 


EARLY   HISTORY  13 

way.  but  although  a  fairly  high  temperature  was  reached  the  sulphur  never 

caught  fire.  The  heat  set  free  by  the  slaking  of  the  lime  would  be  ample 
to  raise  the  temperature  to  the  ignition  point  if  there  were  no  loss  of  heat, 
but  the  reaction  is  a  slow  one  compared  with  an  explosion,  for  instance,  and 
consequently  much  of  the  heat  is  dissipated.     It  seems  more  probable  that 

the  naphtha  was  simply  discharged  from  a  squirt  or  fire-engine  (sipho),  and 

that  it  was  ignited  by  means  of  a  flame  in  front  of  the  orifice,  and  that  the 
secret  consisted  in  the  method  of  constructing  the  squirt  or  pump,  and  of 
using  it  so  as  not  to  injure  the  users.  If  this  be  so.  the  Greek  fire  did  not 
differ  greatly  from  the  flame-projectors  now  employed  by  the  Germans. 

Later  the  name  "  Greek  fire  "  was  given  also  to  combustible  materials  wild-fire, 
which  were  ignited  and  then  thrown  by  ballistic-  or  other  machines,  and  were 
used  on  land.  These  compositions  were  semi-solid  masses  of  sulphur,  pitch, 
naphtha  and  other  substances  that  burn  readily,  and  when  saltpetre  had 
been  discovered  this  also  was  added.  Such  mixtures  may  more  correctly 
be  called  "  wild-fire."  They  were  much  used  by  the  Moslems  in  the  Crusades. 
Thus  Joinville.  the  faithful  and  devoted  companion  of  St.  Louis  in  the  dis- 
astrous sixth  Crusade  (a.d.  125c).  says  that  '"it  came  flying  through  the  AD.  1250. 
air  like  a  winged  long-tailed  dragon,  ab  ut  the  thickness  of  a  hogshead,  with 
the  report  of  thunder  and  the  velocity  of  lightning  :  and  the  darkness  of 
the  night  was  dispelled  by  this  deadly  illumination.'"  Nevertheless,  the 
Greek  fire  on  this  occasion  did  very  little  damage.  That  men  like  St.  Louis 
and  Joinville.  usually  absolutely  fearless,  should  have  been  terrified  by  such 
a  cause  and  described  it  in  such  exaggerated  language  seems  to  have  been 
due  to  the  fact  that  they  looked  upon  it  as  a  product  of  the  Devil.  By  1250, 
however,  the  Arabs  were  acquainted  with  saltpetre,  and  it  is  quite  likely 
that  they  mixed  some  with  the  incendiary,  causing  it  to  burn  far  more  fiercely. 
Similar  language  is  used  in  describing  the  incendiary  missiles  discharged  by 
the  Moors  in  Spain  in  battles  and  sieges  of  about  the  same  date. 

Saltpetre  (potassium  nitrate)  is  formed  in  the  decomposition  of  animal  and  Saltpetre, 
vegetable  matters.  Under  favourable  conditions  it  forms  an  efflorescence 
on  the  ground.  It  must  have  been  by  the  investigation  of  such  efflorescences 
that  saltpetre  was  first  discovered.  These  efflorescences  are  never  pure 
and  seldom  contain  more  than  a  small  percentage  of  potassium  nitrate.  The 
ancients  did  not  clearly  distinguish  such  deposits  of  saltpetre  from  the  similar 
ones  of  soda  which  are  found  in  some  localities.  The  first  preparation  of 
saltpetre  of  even  moderate  purity  from  such  a  deposit  would  require  con- 
siderable chemical  knowledge,  and  it  could  only  have  been  done  in  a  country 
where  the  deposits  are  plentiful,  that  is.  in  a  country  sufficiently  warm  to 
accelerate  the  decomposition  of  the  organic  matter  and  having  a  regular  and 
prolonged  dry  season  during  which  the  deposit  would  collect  and  not  be 
washed  away.     The  climate  of  Western   Europe  is  consequently  not  favour- 


14 


EXPLOSIVES 


able,  and  moreover  scientific  knowledge  and  investigation  were  very  backward 
in  Europe  in  the  early  Middle  Ages.  The  people  who  were  most  proficient 
in  this  branch  of  knowledge  at  that  time  were  the  Arabs  or  rather  the  Arabic- 
king  people  of  Spain,  Northern  Africa  and  Syria,  and  many  parte  of 
these  countries  have  climates  suitable  for  the  formation  of  saltpetre  deposits. 
Consequently,  it  is  not  surprising  that  it  is  in  Arabic  that  the  first  clear  refer- 
ence to  saltpetre  is  to  be  found.  This  is  in  the  writings  of  Abd  Allah  ibn 
al-Baythar.  a  Spanish  Arab  who  died  at  Damascus  in  124*.  [tseeme  probable 
that  the  Arab-  and  Egyptians  knew  saltpetre  in  a  fairly  pure  -tate  about 
1225. 

The  (  ninese  apparently  became  acquainted  with  saltpetre  at  about  the 
same  period,  and  it  is  possible  that  they  were  the  original  discoverers  of  salt- 
petre. The  Egyptians  called  it  "  Chinese  snow,"  '  and  it  is  significant  that 
Chingis,  the  Mongol  conqueror,  brought  Chinese  engineers  with  him  in  1218 
to  reduce  the  fortifications  of  the  cities  of  Persia.2  The  statements  made 
by  the  early  Jesuit  fathers  as  to  the  great  antiquity  of  the  manufacture  of 
gunpowder  in  China,  have  been  shown  to  be  inaccurate  and  founded  on 
erroneous  translations.3  Marco  Polo,  who  was  in  the  Far  East  from  about 
1274  to  12'.'1.  Bays  concerning  the  city  of  Chan-Glu  in  Part  II..  Chapter  L.. 
of  Ins  book  :  '*  In  this  city  and  the  district  surrounding  it  they  make  great 
quantities  of  salt,  by  the  following  process  ;  in  the  country  is  found  a  sal- 
suginous  earth  ;  upon  this  when  laid  in  heaps,  they  pour  water,  which  in 
it-  passage  through  the  mass  imbibes  the  particles  of  salt,  and  is  then  collected 
in  channels  from  whence  it  is  conveyed  to  very  wide  pans  not  more  than 
four  inches  deep.  In  these  it  is  well  boiled  and  then  left  to  crystallize.  The 
salt  thus  made  is  white  and  good,  and  is  exported  to  various  parts.*'  The 
material  prepared  in  this  way  could  not  fail  to  contain  a  considerable  pro- 
portion of  saltpetre,  moreover  the  soil  in  the  province  of  Che-li.  in  which 
the  city  mentioned  seems  to  have  been  situated,  is  known  to  be  rich  in 
saltpetre.  But  from  Marco  Polo's  statement  it  is  probable  that  the  product 
-  common  salt.  In  fact.,  the  Chinese  appear  to  have  used  saltpetre 
a-  ordinary  salt  even  at  much  later  periods. 

In  the  chronicles  called  Tung-Kkm-Kang-mu  there  is  an  account  of  the 
siege  of  Pien-King  mow  Kai-fung-fu)  in  1232.  and  this  was  translated  into 
French  by  Reinaud  and  Fave  in  the  Journal  Asiatiqut  for  October  1849: 

At  that  time  use  was  made  of  the  ;  ho-pao  '  or  fire  pao.  called  :  Tchin- 

tien-loui  '  or  'thunder  that  shakes  the  sky.'     For  this  purpose  an  iron  pot 

1  which  was  filled  with  '  yo."     As  -non  as  a  light  was  applied,  the 

pao  rose  and  fire  spread  in  every  direction.     Its  noise  resembled  that  of  thunder 


1  Hi;  d  Ammunition,  p.   17. 

•  Hime,  chap.  vii. 


:  Gibbon,  chap,  lxiv 


EARLY  HISTORY  15 

and  could  be  heard  more  than  100  lis  (thirty-three  English  miles)  ;  it  could 
spread  lire  over  more  than  a  third  of  an  acre.  This  tire  even  penetrated, 
the  breast  plates  on  which  it  fell." 

"  The  Mongols  constructed  with  ox-hides  a  passage  which  enabled  them 
to  reach  right  to  the  foot  of  the  rampart.  They  commenced  to  sap  the  walls, 
and  made  holes  in  them  in  which  they  could  remain  sheltered  from  the  men 
above.  One  of  the  besieged  proposed  that  they  should  hang  fire-paos  from 
iron  chains  and  let  them  down  the  face  of  the  wall.  When  they  reached 
the  places  that  were  mined,  the  paos  burst  and  shattered  the  enemies  and 
the  ox-hides,  so  as  not  to  leave  a  vestige  of  them." 

"  In  addition,  the  besieged  had  at  their  disposition  some  '  arrows  of  flying 
fire  '  (fei-ho-tiang)  :  to  an  arrow  was  attached  a  substance  susceptible  of 
taking  fire  ;  the  arrow  flew  suddenly  in  a  straight  line  and  spread  flames 
over  a  width  of  ten  paces.  No  one  dared  approach.  The  fire-paos  and 
arrows  of  flying  fire  were  much  feared  by  the  Mongols." 

This  arrow  may  have  been  a  squib  or  a  rocket,  or  merely  an  arrow  to 
which  a  saltpetre  mixture  was  attached.  The  effects  described  could  hardly 
have  been  produced  without  the  use  of  saltpetre,  nor  the  great  noise  without 
an  explosive,  but  we  need  not  take  literally  the  statement  that  it  could  be 
heard  thirty-three  miles  away. 

By  a.d.  1259  the  Chinese  had  made  a  further  advance.  The  same  annals 
state  :  "  In  the  first  year  of  the  period  Khai-King  was  made  an  appliance 
called  '  tho-ho-tsiang,'  that  is  to  say,  '  lance  with  violent  fire.'  A  '  nest  of 
grains  '  was  introduced  into  a  long  bamboo  tube,  which  was  set  light  to. 
A  violent  flame  came  out  and  then  the  '  nest  of  grains  '  was  shot  forth  with 
a  noise  like  that  of  a  pao,  which  could  be  heard  at  a  distance  of  about  500 
paces."     This  was  evidently  the  device  now  known  as  a  Roman  candle. 

Statements  have  been  made  with  regard  to  the  antiquity  of  gunpowder  The  Indians, 
in  India  upon  similarly  incorrect  evidence.  It  is  improbable  that  the  refining 
of  saltpetre  can  have  been  discovered  in  India,  as  the  habits  of  mind  of  the 
educated  classes  would  prevent  their  interesting  themselves  in  such  matters. 
and  the  institution  of  caste  would  render  it  impossible  for  them  to  handle 
many  of  the  materials  involved.  But  the  same  institution  has  enabled  the 
saltpetre  industry  to  be  developed  very  widely,  when  once  the  process  had 
been  discovered  elsewhere  and  introduced,  as  a  special  caste  of  saltpetre 
workers  was  formed,  and  India  still  supplies  a  large  proportion  of  the  saltpetre 
used.  The  saltpetre  at  first  must  have  been  very  impure,  as  the  methods 
of  refining  it  were  crude. 

About  1249  Roger  Bacon  wrote  an  account  of  the  composition  and  maun-  Friar  Bacon 
fact  ure  of  saltpetre  and  gunpowder  in  his  Dc  Secrctis  and  Opus   Tertium. 
Those  in  the  former  work  are  fairly  full,  but    were  concealed  by  means  of 


Fig.    1.     Portrait    of   Roger  Bv. 
(By   kind   permission   of   Lord    Sackville,   from  a   photograph  by  H.   K.  Corke.) 


16 


EARLY  HISTORY  17 

ciphers,   which,  however,   have  been  deciphered  by  Colonel  Hime  with  great 
ingenuity.1     Bacon's  .statements,  when  not  cryptic,  are  generally  vague. 

In  his  Opus  Tcrtium,  written  about  1250,  a  clearer  passage  has  recently 
been  found  by  Prof.  P.  Duhem  in  a  fragment  discovered  in  the  Bibliotheque 
Nationale,  Paris.  The  following  free  translation  has  been  published  by 
Colonel  Hime  in  the  journal  of  the  Royal  Artillery  for  July  1911  : 

"  From  the  flashing  and  flaming  of  certain  igneous  mixtures  and  the 
terror  inspired  by  their  noise  wonderful  consequences  ensue.  As  a  simple 
example  may  be  mentioned  the  noise  and  flame  generated  by  the  powder, 
known  in  divers  places,  composed  of  saltpetre,  charcoal  and  sulphur.  When 
a  quantity  of  this  powder  no  bigger  than  a  man's  finger  is  wrapped  up  in 
a  piece  of  parchment  and  ignited,  it  explodes  with  a  blinding  flash  and  a 
stunning  noise.  If  a  larger  quantity  were  used,  or  if  the  case  were  made 
of  some  solid  material,  the  explosion  would  of  course  be  much  more  violent, 
and  the  flash  and  din  altogether  unbearable. 

"  If  Greek  fire,  or  any  fire  of  the  same  species,  be  employed,  nothing  can 
resist  the  intensity  of  its  combustion. 

"  These  compositions  may  be  used  at  any  distance  we  please,  so  that  the 
operators  escape  all  hurt  from  them,  while  those  against  whom  they  are 
employed  are  suddenly  filled  with  confusion." 

There  can  be  little  doubt  that  soon  after  the  discovery  of  saltpetre  the  The  Arabs 
Arabs  introduced  it  into  their  "  Greek  fire  "  and  other  incendiaries.  In 
Europe,  saltpetre  must  have  been  more  scarce  than  in  Africa  and  Asia.  More- 
over, the  chivalry  of  Western  Europe  looked  upon  such  means  of  war  with 
horror  and  perhaps  were  half  aware  that  the  use  of  them  must  eventually 
destroy  the  Order. 

In  the  Liber  Ignium  of  Marcus  Grsecus,  which  was  probably  translated 
into  Latin  from  an  Arabic  source  about  1300,2  there  are  several  references 
to  such  mixtures,  but  the  translator  does  not  appear  to  have  understood 
the  subject  he  was  writing  on,  and  consequently  it  is  not  now  possible  to 
be  sure  whether  he  is  endeavouring  to  describe  firebrands,  rockets  or  other 
fire-works.     One  "  flying  fire  "  (ignis  volatilis)  is  composed  of  : 

Resin         .......  1 

Sulphur     .......  1 

Saltpetre  .......         2 

dissolved  in  linseed  oil  and  put  into  a  (hollow)  reed  or  piece  of  wood.     This 
was  apparently  an  incendiary  (wild-fire). 

1  G'uupowtlt "/•  and  Ammunition,  cluip.    viii.      Sn    also  first    edition  of  this  work. 

2  See  Hime,  p.   103.     ,  * 

VOL.  I.  2 


18  EXPLOSIVES 

A  i  ii  >t  her  is  made  of 

Sulphur    .......         1 

Vine  or  willow   charcoal     ....         J 

Saltpetre  .......         6 

These  were  rubbed  down  together  on  a  marble  slal>  and  put  into  a  case 
(tunica)  in  different  manners  according  to  the  effect   to  be  produced.     To 

make  a  loud  noise  the  case  was  to  be  short  and  wide,  and  tilled  only  half  full, 
and  was  to  he  hound  with  strong  iron  wire.  Evidently  this  was  a  cracker 
not  unlike  one  described  by  Bacon.  On  the  other  hand,  the  "  flying  tunica  " 
w;h  In  be  thin  and  long,  and  tilled  with  the  above  powder  well  rammed  in. 
This  was  apparently  an  imperfect  rocket  or  squib.  The  same  work  contains 
a  second  description  of  these  tire-works  (recipes  12,  13,  32.  33).  hut  this  does 
not  help  to  clear  up  the  uncertainties. 

That  the  Arabs  were  probably  using  saltpetre  in  their  firebrands  in  1250, 
i>  shown  by  the  passage  in  Joinville.  quoted  above  (page  13).  At  the  siege 
of  Xiebla.  in  Spain,  in  1257,  we  are  told  that  the  Moors  "launched  stones 
and  darts  from  machines,  and  missiles  of  thunder  and  fire." 

The  Chinese  do  not  appear  to  have  developed  explosives  beyond  this 
point,  or  to  have  made  the  next  step,  namely,  of  causing  the  powder  to  throw 
a  heavy  projectile  instead  of  a  ball  of  fire.  Perhaps  they  made  the  attempt, 
hut   with  disastrous  results  to  themselves. 

This  step  could  only  be  taken  by  a  nation  which  was  at  once  progressive 
and  well  acquainted  with  the  working  of  metals.  For  some  time  the  develop- 
ment of  gunpowder  must  have  been  impeded  by  the  scarcity  and  poor  quality 
of  saltpetre.  Before  any  great  advance  could  be  made,  it  was  necessary 
for  a  considerable  organization  to  grow  up  for  collecting  the  saltpetre  and 
refining  it.  In  the  meantime  all  the  available  supply  was  no  doubt  absorbed 
by  the  makers  of  warlike  combustibles. 

In  the  thirteenth  century,  therefore,  saltpetre  was  known  and  used  from 
China  to  Spain  and  England,  but  before  the  invention  of  fire-arms  its 
utility  can  have  been  but  small.  No  reliable  fuse  having  yet  been  discovered, 
hand  grenades  or  bombs  can  have  been  of  little  use  and  must  have  been  more 
dangerous  to  those  using  them  than  to  the  enemy.  The  lire-works  which 
have  been  alluded  to  must  have  been  very  uncertain  in  their  action  and  not 
without  risk  to  the  fire-worker.  It  does  not  seem  to  have  occurred  to  anyone 
to  use  explosives  to  blow  up  the  walls  of  a  besieged  town  by  mining  under- 
neath and  firing  off  a  large  quantity  ;  the  primitive  powder  was  no  doubt 
too  uncertain  in  its  action  and  its  properties  were  not  well  enough  known. 
There  is  evidence  to  show  that,  for  getting  minerals,  gunpowder  was  not 
used   until   the   seventeenth   century.1 

1  Scr  chap.  ii. 


EARLY   HISTORY  19 

The  real  development  of  gunpowder  and  its  extensive  use  had  to  wait, 
therefore,  for  the  invention  of  the  gun.  It  is  generally  considered  that  this 
was  accomplished  by  the  German  monk  Berthold  Schwartz,  as  he  is  named 
as  the  inventor  in  many  old  manuscripts.  There  is.  however,  a  curious 
inconsistency  about  the  dates  mentioned.  The  year  1380  is  given  by  Flavius 
Blondus.  .Eneas  Sylvius.  Baptista  Saccus  and  many  others  living  in  the 
fifteenth  century.  Other  writers  have  stated  that  the  invention  was  made 
in  135-4.  1390.  and  1393. l  But  on  the  other  hand,  there  is  no  doubt  that 
guns  were  used  much  earlier.  There  is  a  manuscript  in  the  Asiatic  museum 
at  Petrograd  probably  compiled  by  Shems  ed  Din  Mohammed  about  1320 
which  shows  tubes  for  firing  off  both  arrows  and  balls  by  means  of  powder.2 
In  an  illuminated  manuscript  entitled  De  Officii*  Regum,  written  by  Walter 
de  Millemete  in  1325  and  preserved  in  Christ  Church  Library.  Oxford,  there 
is  a  drawing,  reproduced  in  Fig.  2.  of  a  rudimentary  gun  shaped  like  a  bottle, 
and  discharging  a  dart.  A  man  is  applying  a  light  to  the  touch-hole.  On 
February  11,  1326.  the  Republic  of  Venice  ordered  the  provision  of  iron  bullets 
and  metal  cannon  for  the  defence  of  its  castles  and  villages.3  and  in  1338 
cannon  and  powder  were  provided  for  the  protection  of  the  ports  of  Harfleur 
and  l'Heure  against  Edward  III.4 

In  two  frescoes  in  the  church  of  the  former  monastery  of  St.  Leonardo  in 
Leccetto.  near  Siena,  painted  by  Paolo  del  Maestro  Xeri  in  1340  are  shown  a 
large  cylindrical  cannon  discharging  a  spherical  cannon  ball,  and  many  hand- 
guns.5 

In  1331  cannon  were  apparently  used  by  the  Moors  at  the  siege  of  Alicante,6 
and  in  1342  in  the  defence  of  Algeciras  against  Alphonso  XI  of  Castille. 

The  Counts  of  Derby  and  Salisbury  were  present  with  the  Spaniards,  and 
it  is  supposed  that  they  introduced  guns  into  England.  In  the  following  years 
there  are  several  references  in  the  accounts  of  the  "Wardrobe  of  Edward  III  of 
payments  on  account  of  saltpetre.  Thus  Thomas  de  Roldeston.  Clerk  of  the 
King's  Private  Wardrobe  in  the  Tower  of  London,  gives  an  account  for  forty 
shillings  for  making  powder  and  repairing  various  arms  in  the  period  1344  to 
1347  :  '"'  Eidem  Thoma?  super  facturam  pulveris  per  ingeniis  et  emendatione 
diversarum  armaturam  XL  sol/'7  And  an  account  was  discovered  by  Gutt- 
manii  delivered  by  John  Cok.  Clerk  of  the  King's  Great  Wardrobe  for  the  date 

1  Guttmann,  Manufacture  of  Explosives,  1895,  vol.  i.,   pp.  10-11. 

2  O.   Guttmann.   Monumenta  Pulveris  Pyrii. 

s  Libris,  Histoire  des  Sciences  mathematiqucs  en  Italic,  vol.  iv  ,  p.  -1ST  ;  P.  et  S..  vol* 
vii.,  p.   33. 

4  P.  et  S.,  vol.  vii.  p.   34. 

5  See  Guttmann.  Monumenta  Pulveris  Pyrii.   1906. 
«  Utescher,  8.  S„  1914,  p.  101. 

7  Guttmann.  Manufacture  of  Explosives,  vol.  i.,  p.  13;  Hunter,  Archceologia,  1847 
YOl,   xxxii. 


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um&jwo&iMinn-taitmiumuisa 
tutflttggm  citrmnf  5  attain*  a 

iIdho.  nW\\v\\io\)imn\(to 
n\iM\\  nuua-iTgivffliitdflicnb1 
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a&Hino:iteran^HOiniinwcidicr 

40:earinatcftntafaai9flifcn-pr 

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Vir.i:i!taprquomcarra^mteo 

irtot'i.troiutpiuiamiscMUHU 

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tn&gpcftiiliiattmtrwwrfleTmi 

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C13C 


From  Walter  de  Millemi  pt,   .*•'••    '326, 

(By   kind  permission  of  the   Dean  of  Christ   <  i.-ti-Ii.  Oxford.) 

20 


EARLY  HISTORY  21 

May  10,  1346,  for  912  lbs.  of  saltpetre,  and  886  lbs.  of  quick  sulphur  for  the 
King's  guns  :  *     "  Et  eidem  Thomse  do  Roldeston  per  manus  Willielmi  de 

1  XX 

Stanes  ad  opus  ipsius  Reis  pro  gunnis  suis  I  XXII  lib.  sal  petrae  et  DCCC IIIIVI 

o 

lib.  sulphur  vivi  per  breve  Regis  datum  X  die  Maii  dicto  anno  XX."  When 
all  possible  allowance  has  been  made  for  alterations  in  the  meanings  of  words, 
there  can  be  no  doubt  that  in  1346  King  Edward  had  guns  and  powder.  On 
November  25,  1346,  and  again  on  September  21,  1347,  an  official  order  was 
given  to  buy  all  available  saltpetre  in  the  country.  On  the  first  occasion 
750  lbs.  of  saltpetre  and  310  lbs.  of  sulphur  were  obtained  ;  on  the  second, 
2021  lbs.  of  saltpetre  and  466  lbs.  of  sulphur.  The  price  of  the  saltpetre  was 
ISd.  per  lb.,  of  the  sulphur  Sd. 

At  the  battle  of  Crecy  (August  26,  1346)  guns  were  used  by  the  English. 
The  French  are  also  believed  to  have  possessed  them,  but  apparently  left 
them  behind  in  order  not  to  be  encumbered  with  them  in  their  pursuit  of  the 
English. 

We  see  then  that  saltpetre  became  known  about  1225  and  that  by  1350  Summary, 
fire-arms  were  in  use  to  a  considerable  extent  in  Western  Europe. 

Saltpetre  was  apparently  discovered  by  one  of  the  Oriental  nations,  and 
was  used  for  making  fire-works  and  incendiary  mixtures  both  in  the  East 
and  West,  but  especially  the  East.  The  explosive  properties  of  saltpetre 
mixtures  must  have  been  known  to  many  people  besides  Roger  Bacon,  but 
they  were  of  little  use  until  the  discovery  of  fire-arms,  which  apparently  was 
made  in  Italy  or  Germany  early  in  the  fourteenth  century. 

The  period  of  the  first  development  of  fire-arms  was  in  many  respects  an 
important  one.  The  division  of  the  power  in  Italy,  France  and  Germany 
among  a  great  number  of  petty  rulers  had  given  the  opportunity  for  the 
growth  of  the  free  cities  on  the  one  hand  and  the  Papacy  on  the  other.  The 
latter  had  used  its  power  to  crush  the  Albigeois  in  Southern  France,  the  most 
civilized  and  cultured  people  of  the  time,  and  by  1250  had  extinguished  them 
with  fire  and  sword.  The  free  cities  were  frequently  richer  than  important 
countries,  and  it  was  in  them  that  the  skill  and  knowledge  were  developed 
which  made  it  possible  to  construct  ordnance  and  make  gunpowder.  Only 
in  England  did  the  king  retain  much  power.  In  the  East  the  prestige  of 
Christianity  and  the  "Franks"  was  then  at  its  lowest  ebb,  but  a  steady 
advance  was  to  come.  The  Christian  religion  had  been  extirpated  from 
Africa  and  a  great  part  of  Spain,  and  in  Syria  the  Crusaders  had  finally  failed 
to  retrieve  the  Holy  Sepulchre.  The  Arabs  had  long  since  been  obliged  to 
resign  most  of  their  conquests  to  the  Turks,  who  had  reduced  the  Eastern 
Roman  Empire  to  little  more  than  the  city  of  Constantinople,  and  that  had 
become  the  spoil  alternately  of   French.  Normans.  Venetians  and  Genoese. 

1  Public  Record  Offico,  London,  L.T.R.  Enrolled  Wardrobe  Account   No.  4. 


22  EXPLOSIVES 

The  final  fall  of  the  city  was.  however,  postponed  by  the  appearance  of  another 
race  who  came,  like  the  Turk-,  from  <  Vutial  Asia.  These  were  the  Tartar-  or 
Moguls,  the  greatest  conquerors  known  in  human  history.  Under  Chingis 
they  conquered  China  in  121o  to  1214.  Carizme,  Transoxiana,  and  Persia  in 
121 S  to  1224.  The  cities  of  the  Middle  East  were  reduced  with  the  aid  of  a 
staff  of  skilful  Chinese  engineers,  who  perhaps  brought  with  them  the  secret 
of  saltpetre.     Under  the  sue  ioH  ningis  fire  and  destruction  were  carried 

into  Russia.  Poland  and  Hungary.  At  the  beginning  of  the  fourteenth  century 
the  Mogul  Empire  declined  under  the  civil  wars  which  almost  inevitably 
result  on  the  death  of  a  monarch  in  the  East.     The  Turks  regained  their 

endancy  for  a  time  in  Western  Asia.  In  1361  to  14<>5Timour  or  Tamerlane 
usurped  the  whole  of  Chingis'  Empire  except  China,  and  added  to  it  Northern 
India,  part  of  Syria  and  Asia  Minor. 

But  already  the  forces  were  being  born  which  were  to  revolutionize  the 
world.  In  the  cities  of  Italy.  Germany.  England  and  France  a  spirit  of 
freedom  in  inquiry,  adventure  and  culture  was  arising  which  now  dominates 
the  whole  earth. 

Gibbon  Note. — The  account  of  the  Creek  fire  is  largely  derived  from  Gibbon's 

Dediiu  d  Fall.  Although  this  remarkable  work  was  written  in  the 
eighteenth  century,  yet  such  i>  its  accuracy  that  even  upon  such  a  difficult 
and  technical  matter  as  this,  subsequent  research  has  been  able  to  find  no 
errors  in  the  statements.  In  a  footnote  relating  to  the  discovery  of  gunpowder. 
Gibbon  sa\ 

"  The  vanity,  or  envy  of  shaking  the  established  property  of  fame,  has 
tempted  some  moderns  to  carry  gunpowder  above  the  fourteenth  and  Greek 
fire  above  the  seventh  century.  But  their  evidence,  which  precedes  the 
vulgar  sera  of  the  invention,  is  seldom  clear  or  satisfactory,  and  subsequent 
writer-  may  be  suspected  of  fraud  or  credulity.  In  the  earliest  sieges  some 
combustibles  of  oil  and  sulphur  have  been  used,  and  the  Greek  fire  has 
affinities  with  gunpowder  both  in  nature  and  effects." 


It   i-  impossible  t«»  -urn  the  matter  up  better. 


CHAPTER  II 
DEVELOPMENT  OF   GUNPOWDER 

Early  manufacture  :  Early  powder-making  machinery  :  Incorporating  mill  : 
Stamp  mills  :  Additions  to  gunpowder  :  Corned  powder  :  Pressed  powder  : 
Breaking  down  :  Composition  of  gunpowder  :  Testing  gunpowder  :  Fire-arms  : 
Double-barrelled  guns  :  Rifles  :  Cannon  Projectiles  :  Incendiary  missiles  : 
Shell  :  Fuses  :  Hand-grenades  :  Infernal  machines  :  Fire-works  :  Military  mines  : 

Blasting 

In  the  fourteenth  century  gunpowder  was  only  used  on  a  small  scale  and  Early 
was  made  in  ordinary  houses  with  pestle  and  mortar.  We  hear,  for  instance,  m  n 
that  the  Rathaus  at  Liibeck  was  destroyed  by  fire  in  1360  through  the  care- 
lessness of  powder  makers.1  Berthelot  has  stated  that  there  were  powder 
mills  at  Augsburg  in  1340,  at  Spandau  in  1344  and  Liegnitz  in  1348,2  but 
Feldhaus  could  find  no  confirmation  of  these  statements  in  the  archives  of 
these  towns.  There  is  no  mention  of  gunpowder  or  fire-arms  in  Augsburg 
before  1372  to  1373,  and  the  first  powder  mill  was  erected  at  Spandau  in 
1578.  The  scale  of  operations  gradually  increased,  and  in  1461  we  find  the 
first  mention  of  a  "powder-house"  in  the  Tower  of  London;  powder  was 
made  there  for  many  years,  as  also  in  Porchester  Castle.3  In  the  sixteenth 
century  mills  of  considerable  size  were  in  existence  :  the  Liebfrauenkirche 
in  Liegnitz  suffered  at  this  time  from  the  effects  of  explosions  in  a  mill  near 
by.  In  1554  to  1555  a  gunpowder  mill  is  said  to  have  been  erected  at  Rother- 
hithe,  and  about  1561  George  Evelyn,  the  grandfather  of  John  Evelyn,  the 
diarist,  had  mills  at  Long  Ditton  and  Godstone,  having  learned  the  methods 
of  manufacture  in  Flanders.  A  few  years  later  he  obtained  from  Queen 
Elizabeth  a  monopoly  of  the  manufacture  of  gunpowder,  which  he  and  his 
sons  were  able  to  maintain  more  or  less  until  1636,  when  Samuel  Cordewell 
obtained  the  monopoly,  which  was  abolished  by  Parliament  in  1641,  the 
year  before  the  outbreak  of  the  Civil  War.  George  Evelyn  made  a  fortune 
out  of  gunpowder,  and  some  of  his  sons  did  well,  but  it  is  doubtful  whether 

1   F.  M.   Feldhaus,  S.S.,   1909,  p.  27.",. 
-  Revue  des  deux  Mondes,  Aug.   15,   1891,  p.  817. 

3  Brit-  Exp.  Ind.,  pp.  183  et  seq.     See  also  History  of  tin   Evelyn  Family,  by  Helen 
Evelyn,   1915,  pp.   19  and   26. 

23 


24  EXPLOSIVES 

any  one  else  made  much  money  out  of  it  in  England.  After  the  Restoration 
the  monopoly  of  gunpowder,  as  of  many  other  materials,  was  re-established 
for  a  time,  but  does  not  appear  to  have  been  maintained  long. 

In  the  reign  of  Charles  I  the  contractors  supplied  to  the  Crown  every 
year  24n  lasts  of  gunpowder  at  Id.  or  Hd.  per  lb.,  and  the  Crown  sold  it  again 
at  aboul  a  shilling,  the  retail  price  being  about  Wkl.  A  last  consisted  of  24 
barrels  containing   100  lbs.   each.1 

At  first  gunpowder  was  made  by  simply  pounding  up  the  constituents 
and  mixing  them  together  in  a  mortar.  Often  the  pestle  was  suspended  from 
a  flexible  wooden  rod.  which  acted  as  a  spring  to  assist  the  lifting.  The  very 
earliest  known  example  of  such  an  appliance  is  shown  in  an  illustrated  manu- 
Bcript,  the  "Codex  Germanicus.'"  preserved  in  Munich  (No.  600  of  the  Hof-  und 
Staatsbibliothek).  Guttmann  assigns  to  this  the  very  early  date  of  1350.1 
Similar  pictures  appear  in  later  manuscripts,  such  as  the  "  Rust  und  feuerwerck 
biiyeh  "  of  the  fifteenth  century,  in  the  Stadtbibliothek  at  Frankfurt  a  .M. 
The  latter  also  shows  the  next  step  in  the  adoption  of  machinery,  the  stamp 
mill.  Guttmann,  in  his  Monumenta  Pirfveri*  Pyrii,  gives  reproductions  of 
many  old  drawings  of  such  plant.  In  the  fifteenth  and  sixteenth  centuries 
there  were  generally  two  stamps  working  in  each  mortar.  They  were  raised 
alternately  by  a  cam  projecting  from  an  axle  which  was  turned  by  hand.  At 
a  later  date  water  wheels  and  treadmills  were  used  as  the  motive  power,  and 
only  one  stamp  worked  in  each  mortar.     Horses  do  not  seem  to  have  been  used. 

There  is  a  picture  of  an  incorporating  mill  with  an  edge-runner  in  a  book 
entitled  Corona  e  Palma  Militare  di  Artcglicria  by  A.  Capo  Bianco,  and 
published  at  Venice  in  1508.  It  has  only  one  edge-runner,  and  the  machine 
is  apparently  turned  by  a  horse  working  in  the  same  building. 

Stamp  mills  were  still  used  extensively  on  the  Continent  at  the  end  of 
the  nineteenth  century,  but  in  England  they  were  forbidden.  Tilt  hammers 
were  also  used  sometimes,  especially  in  Switzerland,  and  in  more  modern 
times  rotating  drums  containing  hard  wood  balls  have  been  employed. 

At  first  the  powder  was  used  in  the  fine  state.  In  this  condition  it  binned 
slowly,  as  the  interstices  were  very  small:  it  was  liable  to  foul  the  fire-arm 
very  badly  after  a  few  rounds,  and  it  was  difficult  to  regulate  the  effect,  which 
depended  very  much  upon  the  ramming.  Bourne,  in  his  Art  of  Shooting 
u  Great  Ordnance,  1587,  said  :  "  The  powder  rammed  too  hard  and  the  wad 
also,  it  will  be  long  before  the  piece  goes  off.  .  .  .  The  powder  too  loose  .  .  . 
will  make  the  shotte  to  come  short  of  the  mark.  .  .  .  Put  up  the  powder 
with  the  rammer  head  Bomewhat  close,  but  beat  it  not  too  hard.""  Other 
disadvantages  of  the  fine  powder  were  thai  it  absorbed  moisture  very  rapidly, 
and  the  constituents  were  liable  to  separate  oik  from  the  other  if  the  powder 
were  subjected  to  much  vibration.  For  although  amorphous  carbon  has 
1  Brit.  Exp.   I  ml.,  p.  278.  -'   Mommenta,  p.   19,  Fig.  48. 


nOKKTr  URKAjfr 

*  C.  State  Coilem, 


DEVELOPMENT   OF   GUNPOWDER  25 

much  the  same  absolute  density  as  saltpetre  and  sulphur,  powdered  charcoal 
contains  many  cavities  which  make  it  lighter  than  the  other  constituents. 

It  was  partly  to  prevent  this  separation  of  the  constituents  that  the  early  Additions  t 
powder-makers  added  camphor,  sal  ammoniac  and  gum  dissolved  in  spirit  Kunpowder 
to  their  powder.  Thus  in  the  "  Codex  Germanicus  "  of  the  fourteenth  century 
the  following  recipe  is  given  :  "  Wiltu  ein  gut  starck  pulver  machen  Ho  nym 
IIII  lb  Salniter  und  I  lb  swebel  und  I  lb  kol/  1  uncz  salpetri  und  I  uncz  salar- 
maniak  Item  und  ainen  XII  tail  campfer  und  stoz  daz  alls  wol  undeinand/ 
und  tu  gepranten  wein  darczu  und  stoss  damit  ab.  und  derre  daz  wol  an 
der  sunn/ so  hastu  ein  uberstarck  beliwig  pulver/  dez  phunt  mer  tut  denn 
sust  III  phunt  getun  mochten  /und  ist  auch  behaltig  und  wirt  lenger  pesser." 

Translation  :  "If  you  want  to  make  a  good  strong  powder,  take  4  1b. 
of  saltpetre,  1  lb.  of  sulphur  and  1  lb.  of  charcoal,  1  oz.  of  salpratica  and  1  oz. 
of  sal  ammoniac  and  one-twelfth  part  of  camphor.  Pound  it  all  well  up 
together,  and  add  spirit  of  wine  and  mix  it  in,  and  dry  in  the  sun.  Then 
you  have  a  very  strong  powder,  of  which  1  lb.  will  do  more  than  3  lb.  other- 
wise.    It  also  keeps  well  and  becomes  better  with  time." 

In  another  part  of  the  same  manuscript  it  is  stated  :  "  Wenn  wa  nicht 
gampfer  pey  ist  daz  pulver  erwirt  und  verdirbt  gern.  Aber  daz  gamfer  halt 
allez  pulver  auf/  und  ist  auch  kreftig  und  prunstig  in  allem  pulver  wenn 
man  in  darin  tut,"  Translation  :  "  When  there  is  no  camphor,  it  crumbles 
and  easily  spoils.  But  the  camphor  holds  all  powder  together,  and  is  also 
strong  and  quick  in  all  powder,  if  one  puts  it  in." 

"  Salpratica  "  was  a  mixture  of  saltpetre,  camphor  and  sal  ammoniac, 
made  by  dissolving  them  all  in  spirit,  placing  the  mixture  in  an  unglazed 
earthenware  vessel,  and  scraping  off  the  efflorescence  that  was  formed.  The 
composition  must  have  been  very  variable.  These  volatile  materials  were 
also  supposed  to  improve  the  power  of  the  explosive  by  increasing  the  amount 
of  "  air." 

The  separation  of  the  ingredients  was  restrained  at  a  later  date  by  "  corn-  corned 
ing  "  the  powder,  that  is,  breaking  the  cakes  into  small  grains  only,  instead  powder, 
of  to  a  fine  powder.     In  order  to  get  a  hard  mill-cake,  which  would  give  good 
grains,  the  contents  of  the  mortar  were  moistened  before  the  end  of  the  stamp- 
ing operation  with  water,  wine  or  urine.     After  it  had  been  broken  down 
the  grains  of  the  required  size  were  separated  by  sifting. 

The  earliest  known  reference  to  corned  powder  is  in  the  "  Firebook  " 
of  Conrad  von  Sehongau  dated  1425. »  It  left  less  fouling  in  the  fire-arm 
and  burned  faster  and  more  regularly  than  the  very  tine  powder,  but  it  deve- 
loped greater  pressure  and  consequently  it  could  not  be  used  in  the  ordnance 
of  the  time,  but  only  in  hand-guns.  The  fine  powder  came  to  be  called  "  ser- 
pentine," apparently  from  the  name  of  the  small  cannon. 

1  M.  Jahns,  Qe8chichte  des  Kriegswesens,  Leipzig.  1880. 


26 


EXPLOSIVES 


Whitehorne,  in  hi-*  Certain  Waies  for  th*  Ordering  of  Souldiers  in  Battelray, 
L560,  Baya  :    "  If  Berpentine  powder  Bhould  be  occupied  (used)  in  handguns, 

it  would  scant  be  able  to  drive  their  pellets  a  quoit*.-  casl  from  their  mouths  ; 
and  if  handgun  (t.e.  corned)  powder  should  be  used  in  pieces  of  ordnance, 
without  great  discretion,  it  would  quickly  break  or  mar  them/' 

According  to  Guttmann.  the  French  powder-mills  began  in  1525  to  grain 
and  classify  their  powder  by  passing  it  through  sieve-.1  Apparently  corned 
powder  came  gradually  into  use  for  small-anus  and  hand-grenades  during  the 
fifteenth  century,  and  for  big  guns  in  the  sixteenth,  the  construction  of  these 
being  sufficient ly  improved  by  that  time.  In  an  engraving  by  Phillip  Galle, 
after  a  drawing  by  John  Stradanus,  to  which  the  date  157o  has  been  assigned,1 
the  operations  of  casting  and  finishing  guns  are  shown,  and  the  manufacture 
had  evidently  reached  a  fairly  high  state  of  development  by  that  time. 

A  really  hard  compact  grain  could  not  be  made  by  this  method,  conse- 
quently after  a  time  presses  were  introduced  to  compress  the  mill-cake  before 
corning.  According  to  Guttmann  3  presses  were  first  used  for  this  purpose  in 
L784.  At  Faversham  in  1789  the  powder  was  compressed  by  means  of  a 
screw  press,  shown  in  drawings  in  a  contemporary  note-book.4  In  the 
nineteenth  century  hydraulic  presses  were  introduced. 

The  cake  was  broken  down  by  hand  with  wooden  mallets,  and  then  pressed 
through  sieves  to  granulate  and  sort  it.  At  one  time  wooden  rollers  were 
used  to  pre--  it  through  the  sieves,  but  later  discs  of  lignum  vitae  were  placed 
in  the  sieves,  which  were  suspended  by  means  of  cords  and  swung  backwards 
and  forwards.  Colonel  Congreve  in  1819  introduced  his  granulating  machine, 
which  iv  described  in  Chapter  VI. 

Colonel  Hime  has  given  tables  to  show  the  development  that  took  place 
in  the  composition  of  gunpowder  in  the  course  of  time.  With  some  alterations 
these  are  reproduced  here  : 


F.M. I. ISM    (U'NPOWDER 


Date 

Authority 

Saltpetre 

•  luwToal 

Sulphur 

L260 

Roger  Bacon    .... 

41-2 

29-4 

29-4 

1350 

Arderne  (Laboratory  receipt) 

66-6 

22-2 

11-1 

1660 

Whitehorne       .... 

50-0 

33-3 

16*6 

it;:',.-, 

Government  contract 

75*6 

12-5 

12-S 

1670 

Sir  J.  Turner  .... 

71  -4 

u:{ 

u:} 

1741' 

Robins     ..... 

76-0 

12-6 

12-fi 

1781 

Bishop  Watson 

75-0 

I.VN 

in. it 

1   Manufacture,  vol.  i.,  p.   17. 
s  Manufacture,  vol.  Li.,  p.  204. 


-  Monumt  nta,  Fig.   S, 

1   B    t.  Exp.   Ind.,  Fig.    13  and  p.  36. 


DEVELOPMENT   OF   GUNPOWDER 

Foreign  Gunpowder 


27 


Date 

Country 

Salt  i  h  i  re 

i'harcoal 

Sulphur 

14th  Century 

Germany.           .... 

66-6 

16-6 

16-6 

1560 

Sweden     . 

66-6 

16-6 

16-6 

1595 

Germany . 

52-2 

26-1 

21-7 

1598 

France 

75-0 

12-5 

12-5 

1608 

Denmark . 

68-3 

23-2 

8-5 

1697 

Sweden    . 

73-0 

17-0 

10-0 

1882 

Germany . 

78-0 

19-0 

3-0 

The  proportions  6:1:1,  known  as  "as,  as,  six,"  were  first  adopted  in 
France  at  the  end  of  the  sixteenth  century  and  have  been  adhered  to  there 
more  or  less  ever  since.1 

The  fourteenth-century  German  powder  has  been  substituted  for  a  French 
powder  of  about  the  same  date  mentioned  by  Hime,  as  it  is  a  more  satisfactory 
example.  The  last  item  in  the  list  is  German  cocoa  powder,  ballistically  the 
best  "  black  "  powder  ever  made. 

But  in  reality  the  composition  was  extremely  variable.  Every  powder- 
maker  had  his  own  formula  in  early  days,  and  in  the  absence  of  testing  appa- 
ratus there  was  no  means  of  judging  which  was  best.  With  the  invention 
of  corned  powder  another  variable  was  introduced,  the  size  of  the  grains, 
and  the  confusion  became  still  worse. 

In  the  Middle  Ages  the  only  tests  applied  to  powder  were  to  feel  it  to  Testing  gu 
ascertain  whether  it  was  moist,  and  to1  burn  a  little  to  see  whether  much  P°wder- 
residue  was  left.     The  first  instrument  for  testing  powder,  of  which  we  have 
any  knowledge,  is  that  described  by  Bourne  in  his  Inventions  and  Devices, 
published  in  1578.     It  was  a  small  metal  cylinder  with  a  heavy  lid  on  -a  1578. 
hinge.      The  lid  was  prevented  from   falling   by  a   ratchet,   and  the  angle 
to    which    it    rose    when    powder    was    fired    inside    the   box    measured   its 
strength. 

A  much  better  instrument  was  that  devised  by  Curtenbach  and  described  1627. 
by  him  in  his  Halinitro  Pyrobolia,  in  1627.  This  consisted  of  a  heavy  conical 
shot  which  rested  on  the  mouth  of  a  small  mortar  and  could  travel  vertically 
upwards  along  a  stretched  wire.  It  was  prevented  from  falling  again  by 
a  series  of  catches.  There  is  a  copy  of  this  in  the  Imperial  Museum  in  Vienna, 
and  Guttmann  gives  a  reproduction  of  a  photograph  of  it  as  Fig.  67  of 
Monument' i  Pulvis  Pyrii. 

Master-Gunner  Nye,  in  his  Art  of  Gunnery,    1647,   described  the  same  1647. 
instrument,  and  also  proposed  that  the  strength  of  powder  be  measured  by 


1  Chalon,  Explosif.s  Modernes,  p.  228. 


28  EXPLOSIVES 

firing  bullets  from  a  pistol  into  clay,  or  by  firing  a  heavy  ball  from  a  mortar 
and  finding  out  how  far  it  travelled.  This  last,  the  mortar  eprouvcttc,  was 
adopted  by  the  French  and  other  Governments,  and  Led  to  considerable 
improvements  in  the  powders.  By  the  beginning  <»f  the  eighteenth  century 
the  proportions  of  the  constituents  were  fairly  well  fixed,  and  the  powders 
for  different  guns  differed  only  in  the  size  of  grain.  In  1742  Robins  placed 
the  matter  on  a  more  scientific  basis  by  the  invention  of  the  ballistic  pendulum, 
by  means  of  which  the  actual  velocity  of  a.  projectile  could  he  measured.  By 
the  end  of  the  century,  practically  every  country  had  come  to  use  the 
proportions,  75  of  Baltpetre,   1~>  of  charcoal,  and  in  of  sulphur. 

To  trace  in  detail  the  development  of  fire-arms  i-  beyond  the  scope  of 
this  work.  Moreover  it  ha-  depended  far  more  upon  the  engineer  than  the 
powder-maker,  who  has  nearly  always  been  able  to  supply  powder  more 
powerful  than  the  gun-maker  has  been  able  to  use,  through  insufficient  engineer- 
ing skill.  At  first  the  chivalry  of  Western  Europe  was  entirely  opposed  to 
the  use  of  fire-arms,  but  it  soon  had  to  acquiesce  in  the  employment  of  gun 
p  .wder  in  warfare,  but  made  a  longer  struggle  as  regards  the  hunting  of 
animals.  Hawking  and  the  chase  were  the  only  respectable  forms  of  sport, 
but  poachers  were  not  governed  by  the  same  scruples,  and  laws  were  conse- 
quently passed  to  prevent  the  use  of  fire-arms  by  them.  For  instance,  in 
L555  the  Elector  Augustus,  of  Saxony,  prohibited  the  possession  of  fire-arms 
by  peasants  and  shepherds,  and  in  1562  small  shot  was  absolutely  prohibited 
throughout  the  Duchy  of  Mecklenburg.1  Nevertheless,  it  was  not  possible 
to  prevent  the  use  of  military  muskets  for  sporting  purposes.  Italy,  in  this 
respect,  as  in  so  many  others,  was  ahead  of  Northern  Europe.  Benvenuto 
Cellini  (/>.  1500,  '/.  1571)  when  a  young  man  was  very  fond  of  -hooting  for 
sport,  and  made  his  own  gunpowder.  He  shot  with  a  single  bullet  and  boasted 
of  his  skill  as  a  marksman.  He  makes  no  mention  of  there  being  any  ]  refudice 
or  law  against   the  use  of  fire-arms.2 

It  was  not  until  the  double-barrelled  gun  was  introduced  that  there  was 
any  real  difference  between  the  military  and  sporting  weapons.  Double 
guns  were  first  made  sufficiently  light  to  be  practicable  in  the  middle  of  the 
seventeenth  century  ;  in  the  eighteenth  century  the  ribs  were  added,  and 
the  Hint    lock  and  hammer  were  introduced. 

Rifles  were  already  known  in  the  first  half  of  the  sixteenth  century,  and 
are  said  to  have  been  invented  by  Augustus  Kotter,  of  Nuremberg,  in  1520, 
but  for  a  long  time  the  rifle  was  used  principally  for  sporting  purposes,  '  ecause 
the  necessity  of  ramming  the  bullet  down  the  band  with  it-  Bpiral  ^i""viiiLr 
made  the  loading  very  slow.  .Moreover,  the  powder  left  much  fouling  in  the 
groove.-,  ami  consequently  it  was  necessary  to  clean  the  arm  after  a  few  rounds. 

1  Greener,  Modern  si,<>t  Ouns,  2ml  ed.,  p.   1. 
-   Vita  di  Jl<  a'-,  i, Hi"  Cellini,  pari  i. 


DEVELOPMENT    OF   GUNPOWDER  29 

With  the  old  musket,  on  the  other  hand,  the  bullet  was  smaller  than  the  bore, 
and  this  trouble  did  not  arise  to  anything  like  the  same  extent.  In  the  seven- 
teenth century  the  rifle  was  tried  in  several  continental  armies,  but  in  every 
case  it  was  given  up  again.1  For  sporting  purposes  accuracy  was  of  more 
importance  than  rapidity  of  tire,  and  the  rifle  was  able  to  hold  its  own,  espe- 
cially in  mountainous  countries  such  as  the  Tyrol  and  Switzerland.  In  the 
American  War  of  Independence  the  sporting  rifle  was  necessarily  used  for 
military  purposes,  and  the  English  Government  found  it  advisable  to  enlist 
on  the  Continent  a  corps  of  "  Jagers  "  to  put  against  the  colonial  marksmen. 
Afterwards  the  Rifle  Brigade  was  raised,  and  this  proved  a  success  from  the 
first.  Robins,  the  inventor  of  the  ballistic  pendulum,  had  already  prophesied 
that  wonderful  effects  would  be  produced  by  the  State  which  could  first  make 
the  military  rifle  a  practical  success. 

Since  then  every  part  of  the  rifle  has  been  further  improved  :  the  action, 
the  rifling,  the  sights  ;  and  magazines  have  been  added  to  increase  the  rate 
of  fire.  In  1886  smokeless  powder  for  rifles  was  introduced,  and  this  has 
added  greatly  to  the  efficiency  of  the  weapon.  The  final  development  is 
the  introduction  of  automatic  rifles  and  machine  guns,  such  as  that  of  Maxim, 
but  this  part  of  the  evolution  of  small-arms  is  still  in  progress.  The  develop- 
ment of  the  pistol  has  proceeded  on  similar  lines. 

The  first  guns  were  tubes  or  pots,  which  could  withstand  only  very  slight  canncn. 
pressures.  Then  they  were  made  of  strips  of  wrought  iron  welded  together. 
By  the  sixteenth  century  they  were  being  cast  in  bronze,  and  by  the  eighteenth 
in  iron.  Until  the  second  half  of  the  nineteenth  century  a  gun  consisted 
simply  of  a  block  of  cast  metal  with  a  smooth  bore  machined  out  and  a  vent 
drilled  near  the  breech.  It  is  true  that  breech-loading  guns  were  made  at 
a  much  earlier  date,  for  examples  of  them  may  be  seen  in  the  museums,  but 
the  crudity  of  the  workmanship  is  sufficient  to  explain  why  they  were  given 
up  again.  In  the  Crimean  war  (1854)  many  of  the  guns  used  had  seen  service 
in  the  Napoleonic  campaigns.  In  1858  a  committee  recommended  the  intro- 
duction of  rifled  ordnance  into  the  British  naval  service,  and  from  that  time 
there  has  been  rapid  and  continuous  improvement  in  all  sorts  of  guns.  The 
introduction  of  the  buffer  has  made  the  guns  much  steadier  ;  breech-loading 
guns  were  re-introduced,  and  the  mechanism  of  the  breech  has  since  then 
been  improved  enormously. 

To  meet  the  recpiirements  of  the  longer  and  more  accurate  guns  the  grains 
of  the  powder  were  gradually  increased  in  size  so  as  to  make  them  burn  more 
slowly.  In  1871  Pebble  or  P  powder  was  made  by  cutting  cubes  from  pressed 
slabs,  and  in  1  SSI  Prism  powder  was  made  by  moulding  hexagonal  prisms 
and  pressing  them  in  a  special  press.  The  Germans  in  L882  made  a  brown 
prism  powder,  and  in  spite  of  attempts  to  keep  the  method  of  manufacture 
*  Textbook  of  SmaU-Arms,    1909,  pp.  6,  7, 


30  EXPLOSIVES 

secret,  it  was  being  made  at  Waltham  Abbey  also  two  years  later.  This 
very  large  and  dense  powder  was  required  on  account  of  the  great  increase  in 

the  size  <>f  naval  guns.  In  1882  at  the  bombardment  of  Alexandria  we  had 
80-ton  gnns  of  16-inch  bore,  and  in  1886  110-ton  guns  of  16£-inch  calibre. 
This  powder  did  not  retain  its  importance  long,  however,  for  in  the  nineties 
smokeless  powder  entirely  displaced  black  powder  as  a  propulsive  explosive 
in  cannon.  With  smokeless  powder  it  is  now  possible  to  throw  a  shell  weighing 
a  ton  a  distance  of  twenty  mill 

The  first  projectiles  used  were  made  more  or  less  like  arrows  with  metal 
"feathers'"  and  arrow-heads,3  just  as  the  first  railway  carriages  were  built 
like  stage-coaches.  These  were  soon  found  to  be  unsuitable  and  were  replaced 
by  round  shot  made  of  iron,  bronze,  lead  or  stone.  All  these  materials  re- 
mained in  use  for  several  centuries,  but  stone  was  the  most  common  for  large 
guns,  partly  because  it-  cost  was  only  a  fraction  of  that  of  a  metal  >hot  of 
the  same  size,  and  partly  because  the  guns  would  not  stand  the  strain  of 
discharging  the  heavier  materials.  Lead  and  iron  bullets  were  usually  used 
for  small-arms,  but  in  an  emergency  any  small  handy  article  was  made 
use  of. 

Attempts  were  made  very  early  to  throw  from  guns  incendiary  missiles 
such  as  had  been  discharged  previously  from  machines,  but  some  difficult  y 
must  have  been  experienced  from  the  flames  being  extinguished  by  the  rapid 
motion  through  the  air.  At  the  siege  of  Weissenburg  in  1469  stone  balls 
were  used  considerably  smaller  than  the  bore  of  the  gun,  and  these  were 
smeared  over  with  incendiary  matter  and  wrapped  in  a  cloth  soaked  in  the 
same  mixture.2 

Actual  shell  could  not  be  used  at  that  time,  because  it  was  not  known 
how  to  cast  them  in  metal.  But  a  sort  of  weak  shell  was  made  of  earthen- 
ware, or  by  joining  two  hemispheres  of  metal.  These  were  filled  with  a  slow- 
burning  powder  well  rammed  in.  or  other  incendiary  matter,  and  were  provided 
with  an  igniter,  which  was  set  light  to  by  the  flame  from  the  gunpowder  of 
the  propelling  charge,  but  there  must  have  been  considerable  uncertainty 
about  the  ignition,  and  of  course  it  was  much  too  dangerous  to  introduce 
a  lighted  shell  into  the  bore  of  a  gun  which  had  been  charged  with  serpentine 
powder  by  means  of  a  shovel.  The  difficulty  was  Bometimes  overcome  by 
enclosing  the  powder  in  a  paper  cartridge,  but  this  method  did  not  find  general 
acceptance.  Red-hot  shot  could  not  be  used  for  the  same  reason,  until  Stephen 
Bathorv.  King  of  Poland,  in  1579  used  a  thick  wet  wad  to  prevent  the  fire 
idinur  to  the  charge.  Hot  shot  were  used  with  great  effect  in  the  defence 
of  Gibraltar  by  the  English  in   1782. 

Solid  -hot  are  nol  u»  d  now  except  for  practice  and  experimental  purposes. 

'.  Ti».  71  ;   Bime,  p.  \w  ■.   fliae  and  Progress,  Fig.  3, 
I   Bime,  p.  220, 


DEVELOPMENT   OF   GUNPOWDKK  3] 

The  shell  for  the  early  muzzle-loading  rifled  guns  were  provided  with 
studs  to  fit  into  the  rifling  and  with  copper  plates  (gas-checks)  over  the  base 
to  prevent  the  escape  of  the  gases  past  the  shell.  For  some  of  the  early  rifled 
breech-loading  guns  the  shell  were  coated  with  lead,  but  now  the}'  are  provided 
with  copper  bands  near  the  base  to  take  the  rifling  and  prevent  the  escape 
of  the  gases.  Originally  of  course  shell  were  filled  with  black  powder,  but 
now  high  explosives  are  used  almost  exclusively  for  common  shell.  Shrapnel 
shell  were  devised  about  1784  by  Lieutenant  Shrapnel  for  use  against  troops 
in  the  open.  They  were  adopted  officially  in  1803  and  consisted  of  a  round 
shell  containing  only  a  small  charge  of  powder,  just  sufficient  to  break  the 
envelope  into  fragments,  which  continued  to  travel  more  or  less  in  the  same 
direction  and  with  the  same  velocity  as  the  shell  did  before.  After  the  intro- 
duction of  rifled  cannon  the  Shrapnel  shell  developed  into  a  cylindrical  missile 
filled  with  bullets  embedded  in  rosin  with  a  small  charge  of  black  powder, 
which,  when  ignited  by  a  time  fuse,  expels  the  bullets.  Against  troops  in 
the  open  its  killing  power  is  great,  but  it  is  ineffective  against  them  when 
entrenched,  and  it  has  not  the  nerve  shattering  effect  of  common  shell  charged 
with  high  explosive. 

Formerly  case  shot  was  used  against  troops  at  short  range.  It  consisted 
of  a  case  containing  a  large  number  of  bullets,  which  spread  out  from  the 
muzzle  of  the  gun,  the  case  being  broken  up  in  the  bore.  The  principal  sorts 
of  case  shot  were  grape,  canister  and  spherical  case.  They  are  not  used 
much  now,  as  their  place  has  been  taken  by  shrapnel  shell  and  machine  guns. 
Chain  shot  was  fired  against  the  rigging  of  ships  :  it  consisted  of  two  balls 
or  half  balls  united  by  a  chain,  and  are  said  to  have  been  invented  by  De 
Witt,  Pensioner  of  Holland,  about  1666. 

For  explosive  shell  the  difficulty  was  to  make  a  satisfactory  igniter  or  Fuses, 
fuse.  The  earliest  record  of  realty  successful  explosive  shell  is  in  the  accounts 
on  the  sieges  of  Wachtendonck  and  Bergen-op-Zoom  in  1588,  the  master 
gunner  being  an  Italian  refugee  from  Parma  in  the  employment  of  the  Dutch. 
The  fuses  used  were  apparently  tubes  or  pipes  filled  with  slow-burning  powder, 
which  were  driven  into  the  fuse-hole  of  the  shell,  and  this  type  was  adhered 
to  until  the  middle  of  the  nineteenth  century  and  later,  when  concussion  and 
percussion  fuses  were  invented. 

The  fuses  were  made  to  burn  14  to  20  seconds,  corresponding  to  ranges  of 
1000  to  2000  yards  in  the  mortars,  which  were  always  used  instead  of  ordinary 
guns  for  throwing  shell.  The  shell  were  used  for  the  destruction  of  stone 
fortifications  and  ships  ;  against  men  they  were  not  effective,  as  there  Mas 
usually  plenty  of  time  to  get  away  from  them  before  they  exploded.  Until 
after  the  introduction  of  watches,  which  were  invented  by  Huygens  in  1674, 
no  convenient  means  existed  of  testing  the  time  of  burning  of  a  fuse.  In 
the  middle  of  the  eighteenth  century  fuses  were  made  of  beechwood  with 


32  EXPLOSIVES 

a  bole  down  the  middle  filled  with  fuse  powder.  The  fuse  could  be  cul  to 
any  required  length.  Great  accuracy  was  not  demanded  <»f  them,  until 
Captain  Merrier  during  the  Biege  of  Gibraltar  in  177'.)  proposed  to  fire  shell 
from  guns  instead  of  howitzers  or  mortals.  Short  "  calculated  "  fuses  were 
then  used  so  as  to  make  the  shell  burst  over  the  Spanish  working  parties. 

The   effect    produced    was   considerable. 

Accurate  fusi  -  were  also  required  for  the  Shrapnel  shell,  which  was  devised 
by   Lieutenant  Shrapnel,   R.A.,  about    17S4.  and  officially  adopted  in    1803, 

but  they  were  made  upon  the  same  principle  until  the  second  half  of  the 
ninet»  enth   century. 

Hand-grenades  stem  to  have  been  used  to  a  considerable  extent  in  the 
first  half  of  the  sixteenth  century,  at  which  lime  they  were  probably  made 
of  earthenware.  They  are  said  to  have  been  used  at  the  siege  of  Aries 
in  L536.1  Whitehorne,  writing  in  1560,  says  that  "earthen  bottles  or  posses'9 
had  been  formerly  used,  but  he  recommends  "  hollow  balks  of  metal,  as  big 
as  Bmal  boulcs  and  J  in.  thick,  cast  in  mouldes  and  made  of  3  partes  of  brasse 
and  1  of  tinne.*'  They  were  charged  with  "  3  partes  serpentine,  3  partes 
tine  corne  powder  and  1  part  rosen."  A  little  fine  corned  powder  was  used 
;i-  priming,  and  he  directs  that  the  grenades  be  "quickly  thrown. "  as  they 
will  almost  immediately  "  breake  and  five  into  a  thousand  pieces." 

In  the  seventeenth  century  the  problem  of  the  fuse  for  hand-grenades 
was  fairly  well  solved,  and  regiments  were  formed  of  "  Grenadiers,"  powerful 
men  specially  trained  to  throw  grenades.  Major  Adye.  writing  in  1802, 
said  grenades  could  be  thrown  twenty-six  yards. - 

The  doubtful  honour  of  having  invented  infernal  machines  is  ascribed 
to  a  Nuremberg  citizen  in  1517,  but  there  is  a  drawing  of  one  by  Leonardo  da 
Vinci,  who  lived  from  1452  to  1519.  In  1645  attempts  were  made  to  blow 
up  Swedish  shi|  s  in  Wismar  harbour  by  means  of  clock-work  bombs.  The 
clock-work  actuated  a  flint  lock  with  a  revolving  steel  wheel.  (lock-work 
infernal  machines  containing  a  nitro-ulycerine  explosive  were  used  also  by 
the  Irish-American  Fenians  in  1883  and  1884,  but  now  clock-work  is  not 
generally  applied  in   these  criminal  attempts. 

Fire-works  seem  to  have  been  made  soon  after  the  discovery  of  gunpowder  : 
references  to  them  arc  found  in  the  writings  of  Sassan-er-Bammah,  Roger 
Bacon.  .Marcus  GrffiCUS,  and  Albertus  Magnus  in  the  thirteenth  and  fourteenth 
centuries.  They  were  probably  made  first  in  China  and  introduced  into 
Europe  in  the  thirteenth  century.  They  were  used  to  celebrate  peace  at 
Yicenza  in  1379."  The  essential  features  were  developed  early,  and  later 
centuries  have  added  nothing  really  novel.  Improvements  have  been  made 
in  the  artistic  effects,  precision  of  execution  and  safety,  but  the  general  prin- 

1  Milildr  WochenbfaU,  Sept.   II,   1915.  -  Hime,  chap.  x. 

:!  A.  Gnadewitz,  8.S.,   1915,  p.  273 


DEVELOPMENT   OF   GUNPOWDER  33 

ciples  are  the  same.  The  introduction  of  chlorates  at  the  end  of  the  eighteenth 
century  has  been  of  some  assistance,  but  their  use  has  been  restricted  on 
account  of  the  dangerous  character  of  many  chlorate  mixtures.  In  the 
seventeenth  and  eighteenth  centuries  large  sums  were  spent  in  Europe  on 
fire-work  displays  to  celebrate  special  events,  but  they  were  not  much  used 
in  war.  Carcasses  containing  incendiary  composition,  smoke-balls  and  light 
balls  were  used,  however,  in  the  Peninsula.1  The  Indians  fired  rockets  in 
the  defence  of  Seringapatam  in  1792,  but  they  do  not  appear  to  have  done 
much  damage.  At  the  siege  of  the  same  town  in  1799  explosive  rockets 
seem  to  have  been  used  with  some  effect.2  Soon  after  this  the  Ordnance 
Office  applied  to  the  Royal  Laboratory,  Woolwich,  for  the  services  of  some 
one  who  understood  the  manufacture  of  rockets.  The  Laboratory  referred 
the  Ordnance  Office  to  the  East  India  Company,  who  replied  that  they  knew 
of  no  one  who  possessed  such  knowledge. 

Colonel  Congreve  of  the  Hanoverian  Army  (afterwards  Sir  W.  Congreve) 
was  thus  led  to  make  exj3eriments,  and  he  devised  the  Congreve  rocket,  the 
most  powerful  thing  of  the  land  that  had  been  used  in  warfare.  It  proved 
very  effective  at  Copenhagen  and  Walcheren  in  1807,  and  at  the  passage  of 
the  Adour  in  1813,  but  it  was  at  the  battle  of  Leipsic  that  it  achieved  the 
greatest  renown,  for  a  French  infantry  brigade  in  the  village  of  Paunsdorf, 
unable  to  withstand  their  well-directed  fire,  surrendered  there  to  the  Rocket 
Brigade.     At  Waterloo  also  good  service  was  rendered. 

Since  the  Napoleonic  wars  the  improvements  in  ordnance  have  been  so 
great  that  the  war  rocket  is  no  longer  used.  For  military  purposes  rockets  are 
only  fired  now  as  signals  and  to  illuminate  the  enemy's  position  at  night,  and 
for  the  latter  purpose  they  have  been  displaced  to  a  great  extent  by  star  shell. 

The  use  of  gunpowder  for  blowing  up  the  enemy's  walls  and  fortifications  Military 
commenced  in  the  fifteenth  century.     Mines  charged  with  gunpowder  were  mines* 
used  in  1415  by  the  English  at  the  siege  of  Honfleur. 

For  blasting  minerals  gunpowder  does  not  appear  to  have  been  used  until  Blasting, 
the  seventeenth  century.  The  first  recorded  blasts  were  made  by  Gaspar 
Weindl  at  Schemnitz,  in  Hungary,  and  from  there  the  method  was  introduced 
into  Germany  in  1627.  Prince  Rupert,  son  of  the  Queen  of  Bohemia  and 
nephew  of  (  harles  I,  is  said  to  have  brought  the  practice  of  blasting  to  England 
in  1 C29.  but  this  is  doubtful  ;  1670  is  a  more  probable  date.3  In  1689  Thomas 
Epsly  Senior  started  the  use  of  gunpowder  in  the  Cornish  mines.4  The  late 
Mr.  Oscar  Guttmann,  in  his  book  on  Blasting,  published  in  1906,  gave  the 
following  concise  account  of  the  further  progress  : 

"  \\  hen  bore-holes  first  came  into  use  they  were  made  with  iron-mouthed 

1  Rise  ini,i  Progress,  p.   17-1.  2  Hime,  p.   12'.). 

3  Brit.  Exp.   /><,/..  p.  255.  «  Feldhaus,  S,S.,   1908,  p.  218. 

VOL.   I,  3 


34  EXPLOSIVES 

borers,  fairly  large     nearly  :i  inches  in  diameter,  and  thru  closed  with  a  wooden 
plug,  termed  the  '  shooting  plug 

"Henning  Hutman  in  1683  employed  a  kind  oi  drilling-machine.  In 
L885  <lay  tampings,  and  in  1686  firing-tubes,  began  to  be  used.  In  L689 
paper  cartridge  cases  were  used  to  replace  the  older  form  of  leather,  and  in 
1717  bore-holes  of  -mailer  diameter  came  into  vogue.  The  use  of  the  chisel- 
borer  dair-  from  I74'.i.  blasting  the  untouched  breasl  from  1 7 r» 7  (first  at 
Zinnwald  ." 

It  i-  only  by  blasting  operations  that  many  of  the  engineering  feats  of 
modern  times  have  been  made  possible.  Tn  constructing  means  of  com- 
municatdon,  such  as  roads,  canals  and  railways,  immense  quantities  of 
explosives  have  been  used. 


CHAPTER   III 

PROGRESS   OF   EXPLOSIVES   IN   THE   EIGHTEENTH   AND 
NINETEENTH  CENTURIES 

Berthollet,  Chlorate  :  Igniters  :  Forsyth's  detonator  lock  :  Fulminates' :  Caps  : 
Fuses  :  Gun-cotton  :  Nitro -glycerine  :  Ammonium  nitrate  explosives  :  Sprengel 
explosives  :  Coal-mine  dangers  :  Cheddite  :  Inspection  of  explosives  :  Smoke- 
less powders  :  Picric  acid   :  Trotyl 

In  the  nineteenth  century  commenced  the  active  application  of  science  to 
explosives,  with  the  result  that  this  industry  like  so  many  others  developed 
enormously.  In  this  chapter  no  attempt  will  be  made  to  give  in  detail  the 
history  of  each  invention  ;  only  the  principal  discoveries  will  be  mentioned, 
and  an  attempt  will  be  made  to  show  how  one  has  led  up  to  and  assisted 
another. 

When  chemistry  was  put  on  a  firm  basis  at  the  end  of  the  eighteenth 
century,  there  was  a  great  increase  in  the  number  of  chemical  compounds 
which  could  be  made  in  the  laboratory.  No  man  had  more  influence  upon 
chemical  science  than  Count  Claude  L.  Berthollet  (1748-1822).  Amongst  Berthollet, 
the  substances  which  he  discovered  was  potassium  chlorate,  or  at  least  he  in 
1786  first  showed  clearly  how  it  could  be  prepared  in  the  pure  state,  and  he 
investigated  and  described  its  properties  ;  for  it  seems  to  have  been  known  to 
Glauber  (1 603-1 G68).  Berthollet  found  that  potassium  chlorate,  if  substituted 
for  saltpetre,  produced  a  more  powerful  (or  violent)  explosive,  and  proposed 
in  1788  to  manufacture  gunpowder  with  it.  But  the  results  were  most 
disastrous.  A  party  had  been  made  up  to  see  the  first  of  the  new  powder 
made  in  the  mills  :  M.  and  Mme.  Lavoisier,  M.  Berthollet,  the  Commissary, 
M.  de  Chevraud  and  his  daughter,  the  engineer,  M.  Lefort,  and  others.  Whilst 
the  mixture  was  being  incorporated  in  a  stamp-mill  the  party  went  to  break- 
fast. Lefort  and  Mile,  de  Chevraud  were  the  first  to  return,  and  as  they  did 
so  the  charge  exploded  with  great  violence,  throwing  them  to  a  great  distance 
and  causing  them  such  injuries  that  they  both  died  in  a  few  minutes. 

In  spite  of  repeated  attempts  it  has  not  been  found  possible  to  make  a 
satisfactory  propulsive  explosive  with  chlorate  ;  the  explosion  is  always  liable 
to  be  too  violent  and  uncontrollable. 

35 


36  EXPLOSIVES 

Until  the  invention  of  Cheddite  all  the  chlorate  mixtures  proposed  were 
too  sensitive  to  be  used  with  safety  even  as  blasting  explosives.  Cundill 
and  Thomson's  Dictionary  of  Explosives  issued  in  L895  includes  the  descriptions 
of  150  mixtures  containing  potassium  chlorate,  but  with  the  exception  of  a 
few  capandfuse  compositions  none  of  these  have  proved  to  be  of  practical  use. 

[^niters.  The  first  fire-arms  were  set  off  by  means  of  a  lighted  match,  which  was 

applied  to  a  priming  of  line  powder.  Bain  or  wind  seriously  interfered  with 
the  operation.  In  the  eighteenth  century  the  flint  lock  was  devised  and  a 
lighted  match  was  no  longer  necessary.  In  its  best  form  the  priming  powder 
was  contained  in  a  small  chamber  which  was  uncovered  only  at  the  instant 
when  the  descending  flint  struck  a  spark  from  the  steel.  Although  this  was 
a  great  improvement  it  left  much  to  be  desired  as  regards  ease  of  loading, 
rapidity  of  ignition,  and  fouling  of  the  touch-hole.  Hence  the  persevering 
attempts  to  devise  an  easier  and  simpler  method. 

?orsyth's  In  1805  the  Rev.  A.  J.  Forsyth,  a  Scotch  minister,  made  a  sporting  gun 

letonatoriock.  with  a  detonator  lock,  and  in  the  next  year  submitted  his  invention  to  the 
Master-General  of  Ordnance,  who  asked  him  to  adapt  it  to  the  requirements 
of  the  Service.  Forsyth's  device  consisted  of  a  receptacle  or  magazine  shaped 
like  a  scent-bottle,  which  was  attached  to  the  lock  of  the  gun.  It  contained 
a  detonating  mixture  of  potassium  chlorate,  charcoal  and  sulphur.  By 
rotating  the  magazine  a  small  quantity  of  this  was  caused  to  fall  into  a  small 
hole  in  a  plug  communicating  with  the  touch-hole  of  the  gun,  and  on  again 
rotating  the  magazine  it  was  brought  into  such  a  position  that  the  portion 
of  detonating  priming  could  be  set  off  by  the  fall  of  the  hammer. 

Forsyth  spent  some  £600  in  trying  to  produce  a  satisfactory  device  for 
military  purposes,  and  he  claimed  to  have  succeeded,  but  the  Government 
authorities  were  not  convinced  and  did  not  adopt  it.  At  the  time  they  only 
paid  Forsyth's  expenses,  but  they  granted  £1000  to  his  relatives  shortly  after 
his  death. 

For  sporting  purposes  Forsyth's  invention  had  some  success,  but  the 
profits  must  have  been  largely  swallowed  up  by  the  numerous  lawsuits  that 
he  instituted  to  protect  it  from  1811  to  1819.  Before  very  many  years  had 
elapsed  Forsyth's  device  was  displaced  by  the  copper  tube  or  cap.  containing 
fulminate  of  mercury. 

Culminates.  Fulminates  of  gold  and  silver  have  long  been  known,  and  their  discovery 

was  ascribed  to  Basil  Valentine,  a  fictitious  person  of  the  fifteenth  century. 
They  were  perhaps  invented  by  Cornelius  Drebbel,  a  Dutchman,  about  1600. 1 
Pepys,  in  his  diary  for  November  11,  1663,  recounts  a  conversation  with  a 
Dr.  Allen,  who  told  him  about  Atirum  fulminans,  "of  which  a  grain  .  .  .  put 
in  a  silver  spoon  and  fired,  will  give  a  blow  like  a  musquetl  and  strike  a  hole 
through  the  silver  spoon  downward,  without  the  least  force  upward," 

1    !•'.   M,    Kddhaus.   S,S„    l'-Hilt.  p.   258, 


PROGRESS   OF   EXPLOSIVES  37 

The  fulminates  of  gold  and  silver  are.  however,  too  sensitive  and  dangerous  { J^^ate 
for  any  practical  use,  but  they  Gave  played  their  part  as  toys  and  scientific 
curiosities.  Liebig.  who  was  born  in  1803.  when  a  boy  saw  a  quack  in  the 
market-place  of  Darmstadt  make  fulminating  silver.  The  alcohol  he  recog- 
nized from  the  smell  of  a  garment  which  the  quack  had  cleaned  with  liquid 
from  the  same  bottle.  He  went  home  and  succeeded  in  making  the  substance. 
In  1823.  when  he  was  in  Paris  with  Gay  Lussac,  he  investigated  the  fulminates 
at  the  suggestion  of  the  latter,  and  isolated  fulminic  acid.  By  that  time  the 
comparatively  stable  fulminate  of  mercury  was  well  known,  having  been 
described  by  Edward  Howard.  F.R.S..  in  a  paper  before  the  Royal  Society 
in   1800.     It  is  stated  that  it  was  manufactured  in  France  in   1819. 

There  is  some  uncertaintv  as  to  who  first  invented  the  fulminate  of  mercury  Fulmmate 

^  •    cap. 

cap,  but  it  seems  that  several  people  were  working  at  the  idea  at  the  same 

time  and  contributed  towards  the  final  success.    According  to  H.  Wilkinson,1 

J.  Shaw,  of  Philadelphia,  invented  a  steel  cap  in  1814  ;   in  1815  a  pewter  cap, 

and  in   1816  a  copper  cap.     The  London  gun-maker.  Joseph  Egg,  seems  to 

have    adopted    the    idea    from    Shaw.     The    Paris    gun-makers.    Prelat    and 

Deboubert,  in  1820  patented  caps  filled  with  fulminates  of  silver  and  mercury 

respectively.     E.   Goode  Wright,   of  Hereford,  in   1823  published  a  paper - 

on  the  fulminate  of  mercury  cap,  and  subsequent  workers  seem  to  have  derived 

much  information  from  it.     Frederick  Joyce  was  the  first  to  make  a  real 

success  of  the  percussion  cap  about  1824.     The  firm  of  Joyce  and  Co.  claim 

an  earlier  date,  but  although  experiments  may  have  been  made   in   previous 

years  there  appears  to  be  no  evidence  of  manufacture  on  a  considerable  scale.3 

The  next  important  step  was  to  combine  shot,  powder  and  cap  in  one  The  capped 
cartridge,  which  could  be  inserted  in  the  breech  of  the  arm.  Many  attempts  cartndge' 
had  been  made  from  very  early  times  to  make  breech-loading  fire-arms,  but 
workmanship  and  knowledge  of  engineering  were  not  sufficiently  advanced 
to  make  a  success  of  it.  In  1836  Lefaucheux  introduced  his  pin-fire  breech- 
loading  shot-gun.  the  barrels  of  which  were  made  to  drop  as  in  the  modern 
shot-gun  to  allow  the  cartridges  to  be  introduced.  This  gun.  although  it  had 
many  imperfections,  combined  all  the  principal  features  of  those  made  at  the 
present  day.  About  1853  the  English  and  French  gun-makers  introduced 
the  central  fire  hammer  gun,  which  fired  cartridges  having  a  cap  in  the  middle 
of  the  base  of  the  cartridges,  but  the  first  really  successful  central  fire  gun 
was  that  made  by  Daw  in   1861.4 

In   1841   the  Prussians  adopted  a   breech-loading  rifle,  the   "  Zundnagel-  loading" rifle 

1  Engines  of  War,  p.    187.  -  Phil.  Mag.,  vol.  lxii.,  p.   203. 

3  Tlic  account  of  the  discovery  of  the  percussion  cap  is  largely  taken  from  the  paper 
by  E.  \\  viulham  Hulme,  B.A..  in  the  Rise  n>nl  Progress  of  the  British  Explosives  Industry, 
London,   1909.     See  also  Utescher,  S.S.,    1914,  p.   101. 

4  Greener,  Modern  Shot  Guns.   2nd   ed.,    1891.  p.   4. 


38  EXPLOSIVES 

gewehr,"  invented  in  ]s:is  l,v  Dreyse.  In  this  ignition  was  effected  by  a 
needle  being  driven  right  through  t lit*  base  of  t he-  cartridge  into  a  disc  of 
fulminating  material.  After  a  few  rounds  the  rifle  could  not  be  fired  from 
the  shoulder  in  consequence  of  the  escape  of  flame.  The  needles  also  i 
and  broke.  .But  in  spite  of  its  defect-  the  gain  in  rapidity  of  fire  caused  it 
to  be  maintained  as  the  general  arm  in  the  wars  of  1848,  1866,  and 
L870.1 

The  French  adopted  the  Chassepol  in  1866.  This  was  a  considerable 
improvement  upon  the  Prussian  rifle  ;  escape  of  gas  at  the  breech  was  pre- 
vented by  mean-  of  a  rubber  washer.  About  the  same  time  a  committee  sat 
in  England  to  decide  upon  a  rifle,  and  finally  selected  that  of  Mr.  Jacob  Snider, 
an  American.  But  at  the  suggestion  of  Colonel  Boxer  the  cartridge 
was  made  of  brass  instead  of  thin  paper  as  in  previous  rifles.  This  not  only 
greatly   improved   the  accuracy  of  shooting,   but    effectually  prevented  the 

ipe  of  gas  at   the  breech.8 

The  old  method  of  firing  a  blasting  charge  Mas  to  lay  a  train  of  powder 
up  to  it.  or  use  a  quill  or  rush  filled  with  powder.  The  time  taken  by  tl 
to  burn  was  very  uncertain,  however,  and  this  caused  numerous  accidents 
in  the  mines.  This  led  Mr.  William  Bickford,  of  Tuekingniill.  Cornwall,  in 
L831  to  devise  his  "  miner's  safety-fuse."'  wherein  a  continuous  thin  core  of 
powder  was  contained  in  cable  of  jute  and  string.3  This  gradually  came 
more  and  more  into  use.  and  the  fuse  was  improved  in  qualify  as  experience 
was  gained  in  its  manufacture.  For  use  in  wet  places  a  special  quality  was 
made  covered  with  tape  and  varnished.  Soon  after  1840  the  Bickford  fuse 
was  adopted  by  the  English  military  authorities.  In  1836  a  factory  was 
-tailed  in  America  ;  in  1839  in  France,  and  in  1844  in  Germany.  Before 
1840  guttapercha-covered  fuse  had  been  adopted  for  blasting  under  water. 
\  arious  modifications  have  since  been  invented,  including  fuse  cased  in  metal. 
'"  Colliery  Fuse,"  which  emits  no  sparks,4  and  various  sorts  of  "  instantaneous 
fuse,"  which  burn  very  rapidly  and  enable  many  shots  to  be  fired 
simultaneously. 

As  stated  in  the  last  chapter  the  fuses  of  shell  were  originally  arranged 
to  be  ignited  by  the  flash  of  the  powder  charge  in  the  gun.  The  invention 
of  the  percussion  cap,  however,  made  it  possible  to  start  the  action  of  the 
fuse  in  another  and  more  certain  manner.  In  1846  Quartermaster  Preeburn, 
R.A.j  invented  the  first  English  time  fuse  started  by  the  concussion  of  the 
discharge;  and  in  1850  Commander  Moorson,  R.N.,  brought  forward  the 
first  percussion  fuse  which  was  actuated  by  the  shock  of  impact  of  the  shell.5 
These  two  type-  of  fuse  are  still  in  use  and  are  made  to  screw  into  either  the 

1  Textbook  of  Small-Arms,  1909,  chap.  ii. 

-'   Textbook  o\  Small-Arms,   1909.  »  Eng.  Pat.  N<>.  6159  of  1831. 

4   Patented  by  Sir  <;.  Smith  in  181  6  Hime,  p.  24.".. 


PROGRESS   OF   EXPLOSIVES  39 

nose  or  base  of  the  shell.  Very  often  both  methods  are  combined  in  a  "  time 
and  percussion  fuse."  Shell  were  used  with  great  effect  by  the  Russian 
fleet  against  the  Turkish  at  Sinope  in  1853.1 

Gun-cotton  was  discovered  in  1845-1846  by  C.  F.  Schonbein,  Professor  Gun-cotton, 
of  Chemistry  at  Basle,  in  the  course  of  some  experiments  which  he  was  making  1846- 
upon  highly  oxidized  bodies,  following  up  a  train  of  thought  suggested  by 
his  discovery  of  ozone  in  1844.     Pelouze  had  made  an  explosive  in  1838  by 
the  action  of  nitric  acid  on  cotton,  but  he  did  not  take  the  important  step  of 
mixing  sulphuric  with  the  nitric  acid,  and  he  did  not  make  any  practicable 
application  of  his  explosive.     Schonbein  at  once  recognized  its  importance  as 
an  explosive  and  kept  the  method  of  preparation  secret,  whilst  he  endeavoured 
to  sell  the  process  to  various  Governments.     He  showed  that  when  fired  in 
a  musket  gun-cotton  produced  the  same  velocity  as  a  much  greater  weight  of 
gunpowder.     Professor  Bottger,  of  Frankfort-on-Main,  discovered  gun-cotton 
in  1846.  independently  of  Schonbein,  but  he  entered  into  an  arrangement  with 
him  to  share  the  profits  of  the  invention.     Several  others,  attracted  by  the 
great  stir  that  was  caused  by  the  invention,  endeavoured  to  make  gun-cotton, 
and  some  of  them  succeeded,  but  Schonbein  was  able   to   maintain  the  start 
he  had  obtained.     In  the  autumn  of  1846  he  came  over  to  England  and  gave 
some  very  successful  demonstrations  at  Woolwich  and  Portsmouth  and  before 
the  British  Association.     In  the  name  of  John  Taylor  he  took  out  a  British 
Patent,2  and  he  entered  into  an  agreement  for  three  years  with  John  Hall 
and  Sons  that  they  should  have  the  sole  right  to  manufacture  gun-cotton  at 
their  powder  works  at  Faversham,  and  in  return  should  pay  one-third  of  the 
net  profit  with  a  minimum  of  £1000  down,  and  the  same  each  year.     But 
before  a  year  had  elapsed,  on  July  14,  1847,  there  was  an  explosion  of  the 
gun-cotton  which  destroyed  the  factory  and  killed  twenty-one  men.     After 
this  Hall  and  Sons  refused  to  proceed  with  the  manufacture.     About  the 
same  time  there   were  disastrous  gun-cotton  explosions  at  Vincennes   and 
Bouchet,  and  these  produced  such  an  effect  that  no  more  gun-cotton  was 
manufactured  in  England  or  France  for  some  sixteen  years. 

Meantime  Schonbein  had  offered  his  process  to  the  German  Union 
(Deutscher  Bund)  for  100,000  thalers,  and  a  committee  had  been  formed 
to  consider  the  matter,  on  which  Liebig  represented  the  state  of  Hesse,  and 
Baron  von  Lenk.  who  was  secretary,  represented  Austria.  This  committee 
sat  until  1 852,  but  finally  refused  to  buy  the  process,  partly  on  political  grounds. 
The  individual  members  of  the  Union  were  then  able  to  make  separate 
negotiations,  and  at  the  suggestion  of  von  Lenk,  who  had  done  most  of  the 
actual  work  of  the  committee,  Austria  accmired  the  process  for  30,000  gulden. 

In  1852  the  Emperor  of  Austria  appointed  a  committee  to  inquire  into  von  Lenk. 
the  use  of  gun-cotton  for  military  purposes,  and  with  some  interruptions  this 
1  Rusch,  S.S.,   1908,  p.   189.  -  No.    I14i>7.   October  8,   18-40. 


40  EXPLOSIVES 

tinned  to  -it  until  1865.     In  l*r>:*  a  factory  ted  at  Hirtenberg  to 

carry  out  von  Leak's  method  of  making  gun-cotton.  In  this  the  purification 
what  more  thorough  than  in  Schdnbein's  origina]  process,  for  instead 
of  merely  washing  with  water  until  neutral.  v<.n  Lenk  washed  Ear  three  weeks, 
then  boiled  with  dilute  potash  Bolution  for  fifteen  minute-.  washed  again 
ral  days,  impregnated  the  yarn  with  water-glass,  and  finally  dried. 
-c  also  constructed  some  batteries  "f  12-pounder  mm-  to  be  fired 
with  gun-cotton  cartridges.  These  mm-  were  bo  much  damaged  by  firing, 
however,  that  no  other  nation-  adopted  them.  About  1860  von  Lenk 
introduced  bronze  Lrun>.  which  were  less  liable  t<»  burst  than  iron  ones,  and 
these  not  only  had  a  propulsive  charge  of  gun-cotton,  but  also  had  shells 
containing  a  bursting  charge  of  the  same  explosive.  It  was  found,  however, 
that  these  often  burst  in  the  bore,  and  this  was  evidently  due  to  the  very 
sudden  shock  of  the  discharge  exploding  the  shell  charge,  for  when  gunpowder 
I  to  fire  the  gun-cotton  shells,  no  bursts  took  place.  On  July  20, 
1863,  the  magazine  at  Hirtenberg  exploded,  and  this  seem-  to  have  finally 
decided  the  Austrian  authorities  to  give  up  gun-cotton  as  a  propulsive 
explosive,  and  von  Lenk  was  then  allowed  to  communicate  the  method  of 
manufacture    to    other    1  In    1865    another    magazine    exploded    on 

Steinfelder  Heath,  near  Vienna,  and  on  October  11.  1865,  the  manufacture 
was  officially  stopped  in  Austria. 

The  further  development  then  took  place  in  other  countries.  Von  Lenk 
made  communications  to  the  Emperor  Napoleon  III.  and  experiments  were 
started  in  France.     In   lsn4  he  took  out  an  American  patent. 

In  l*xi;2  and  1863  von  Lenk  took  out  patents  in  England  in  the  name 
of  Revy  to  protect  his  method-  of  purification,1  an i  in  the  latter  year  he 
came  over  with  the  permission  of  the  Emperor  to  describe  his  process  to  a 
committee  of  the  British  Association.  The  same  year  Messrs.  Prentice  and 
si  -  to  make  gun-cotton  at  Stowmarket  by  von  Lenk's  process,  but 
an  explosion  occurred  there  soon  after. 

Under  the  direction  of  Frederick  Abel,  the  Chemist  of  the  English  War 
Department,  manufacture  wa-  also  started  about  the  same  time  on  a  -mall 
scale  in  the  Royal  Gunpowaer  Factory  at  Waltham  Abbey.  This  made  it 
ssible  for  Abel  to  carry  out  those  experiments  and  researches  which  led 
to  a  revolution  in  the  explosives  industry,  and  have  rendered  gun-cotton 
one  of  the  -afe-t  explosives  in  manufacture  and  use.  In  1865  ho  took  out 
a  patent  for  pulping  gun-cotton  and  pressing  it  into  block-.-  and  in  1  >>•'.(.  and 
1  B67  he  published  hi-  /,'■  lb-  showed  that  by  pulping 

1  K  _ 

2  1  -  S  1102  1861  _  •  .  tton  had,  howi  a  carried 
out  at  L<-  Bouchel  in  Pi  -                      •  -//..  1905,  p.  15). 

3  Phil.   7  Sociei  ..    1866,   ;      I            nd    Is-. 7.  p.    181. 


Progress  of  explosives  41 

gun-cotton  in  the  same  way  as  is  clone  with  rags3  etc.,  in  the  manufacture 
of  paper,  he  not  only  got  it  in  a  more  convenient  state  for  pressing  into  blocks, 
but  the  violent  mechanical  treatment  removed  much  of  the  impurity,  and 
the  gun-cotton  was  reduced  to  a  condition  in  which  it  was  much  easier  to 
wash  it  thoroughly.  The  object  of  compressing  the  pulped  gun-cotton  was  to 
restrain  the  violence  with  which  it  exploded  in  the  gun.1  but  although  it  was 
better  than  von  Lenk*s  yarn  it  was  still  uncontrollable:  it  damaged  the 
guns,  and  the  accuracy  of  the  shooting  was  unsatisfactory.  It  was  not  until 
some  seventeen  years  later  that  a  successful  smokeless  military  powder  was 
made.  Gun-cotton  was  therefore  only  used  for  blasting  purposes.  Prentice 
and  Co..  of  Stowmarket.  adopted  Abel's  process  of  purification  and  have 
continued  to  use  it  ever  since.  In  1868  its  utility  was  much  increased  by  the 
discovery  by  Abel's  assistant.  E.  A.  Brown.2  that  dry  compressed  gun-cotton 
could  be  caused  to  explode  very  violently  by  a  detonator  containing  fulminate 
of  mercury,  this  appliance  having  been  already  used  by  Xcbel  3  for  detonating 
nitro-glycerine.  Brown  afterwards  made  the  further  discovery  that  a  slab  of 
wet  gun-cotton  could  be  exploded  by  means  of  a  small  primer  of  dry  gun-cotton. 
This  rendered  it  possible  to  store  the  greater  part  of  the  gun-cotton  in  the 
wet  state,  a  great  advantage  for  military  purposes,  and  in  this  field  gun-cotton 
as  originally  prepared  under  the  superintendence  of  Abel  still  holds  its  ground 
to  some  extent. 

In  1847  Maynard  discovered  that  nitro-cellulose  was  soluble  in  a  mixture  Other  uses 
of  ether  and  alcohol,  although  it  did  not  dissolve  in  either  liquid  alone,  and  cellulose 
this  led  to  the  invention  of  the  collodion  photography  by  Scott  Archer  in 
1851.  and  to  other  uses  of  collodion.  Celluloid,  made  by  dissolving  nitro- 
cellulose in  camphor  with  the  aid  of  heat  and  pressure,  was  patented  by 
J.  W.  and  I.  S.  Hyatt  in  1870.4  The  artificial  silk  industry  may  be  said  to 
have  started  in  1884  when  Count  Hilaire  de  Chardonnet  took  out  his  first 
patent.5 

In  1846  nitro-glycerine  was  discovered  by  Sobrero.  Professor  of  Chemistry  Nitro- 
at  Turin,  who  had  been  assistant  to  Pelouze  in  1838  when  he  made  his  first  glycerine- 
experiments  on  nitrating  various  bodies.  But  no  practical  application  was 
made  of  it  except  that  very  small  quantities  were  used  in  medicine  as  a  cure 
for  angina  pectoris.  People  were  no  doubt  deterred  by  the  dangerous  nature 
of  the  material  and  the  inconvenience  of  dealing  with  a  liquid  explosive,  as 
also  by  the  difficulty  in  causing  it  to  explode.  In  1859  to  1861,  however. 
Alfred  Xobel  and  his  father  made  experiments  with  it.  and  found  that  it 
could  be  exploded  by  means  of  a  detonator  containing  fulminate,  and  in  1862 

1  See  Chem.  News,   1866,  (4)  p.   250,  ami   1871,   (24)  p.   141. 

2  Eng.  Pat.    No.   3115  of  1868.  3  Eng.  Pat.   No.    1345  of   1867. 

4  Amer.  far.  ln.->.:j:5S.  July  12.  lSTo.     Set  J.  Soc.  Chem.  Ind.,  1914,  \>.  22.".. 

5  French    Pat.    1  •  i. ">.."» 4. ">. 


42  i:xplosivi:> 

commenced  to  manufacture  it  at  Heleneborg,  near  Stockholm,     Many  serious 
accidents  occurred  in  the  transport  and  use  of  the  explosive .  and  in  lst>4  an 
explosion  took  place  at  the  Heleneborg  works,  which  destroyed  them,  killed 
the  head  chemist   and  Nobel's   brother,   and  caused  his  father  a  paralytic 
stroke  from  which  he  never  recovered.     Xobel,  however,  was  not  deterred 
by  this,  and  proceeded  to  re-erect  his  factory  at  Yintervikken.  and  build  a 
new  one  at  Kriimmel  in  Germany.     He  was  convinced  that  nitre-glycerine 
was  the  most  powerful  explosive  known  or  likely  to  be  discovered,  and  in- 
allowed  nothing  to  prevent  him  turning  its  properties  to  profitable  account. 
The    continual    catastrophes,    however,    caused    the    various    states    to    pass 
laws  restricting  or  prohibiting  the  transport  and  use  of  nitre-glycerine.     In 
consequence  Xobel  searched  for  means  to  make  the  material  safer  and  more 
convenient  to  handle,  and  discovered  that  kieselguhr  had  the  power  to  absorb 
three  times  its  weight  of  nitro-glyeerine.1     This,  combined  with  the  fulminate 
detonator  mentioned  in  the  same  specification,  produced  a  very  convenient 
and  fairly  safe  explosive.     Xobel  then  proceeded  to  exploit  his  inventions, 
and  he  did  this  with  such  success  that  by  1873  fifteen  factories  had  been 
built  or  founded  in  the  various  countries  of  Europe  and  America.      In  1875 
he   made    another   important    invention,2    that    of    blasting    gelatine.      The 
nitre-glycerine  in  this  explosive  was  solidified  by  having  about  8  per  cent, 
of  collodion  cotton  dissolved  in  it.     As  compared  with  kieselguhr  dynamite 
this  has  two  advantages  :    the  nitro-glycerine  is  not  liable  to  be  displaced 
from   it    by    water,    a   defect    which   in   the    case    of   dynamite   has   led   to 
many  accidents  ;    and.  secondly,  the  substance  added  is  itself  an  explosive, 
and  consequently  blasting  gelatine  is  25  per  cent,  more  powerful  than  dynamite. 
Gelatinized  nitro-glycerine  containing  a  small  proportion  of  collodion   has 
been  made  a  constituent  of  many  blasting  explosives,  the  nature  of  the  other 
constituents    and    the    method    of   preparation    being    modified    to    produce 
explosives  suitable  for  blasting  different  sorts  of  rock  and  other  materials.3 
In  1867  the  Swedish  chemists,  C.  J.  Ohlsson  and  J.  H.  Norrbin,  took  out 
a  patent  for  explosives  consisting  of  ammonium  nitrate,  either  by  itself  or 
in  admixture  with  other  substances  such  as  charcoal,  sawdust,  naphthalene, 
picric  acid,  nitro-glycerine  or  nitro-benzene.     They  were  led  to  their  invention 
by  theoretical  calculations,  which  showed  that  a  very  large  amount  of  heat 
and  gas  was  given  off  in  the  explosion  of  these  mixtures.     They  selected 
the   proportions    so    that   all    the    carbon    should    be    converted    to    carbon 
dioxide  and  the  hydrogen  to  water.      Considerable  difficulty  was.  however. 
experienced  in  igniting  the  charges,  and  consequently   they   usually  added 
some   nitro-glycerine    to    assist    the    explosion.     Afterwards    they    used    the 

1  Eng.  Pat.  No.    L346  of  1867.  2  Eng.  Pat.   No.   4  I  Tit  of  1875. 

\  very  interesting  account   of  Alfred  Nobel  and  hi^  inventions  was  contributed 
by  de  Moeenthal  to  the  J. S.C.I,  for  1899,  p.  ir.i. 


PROGRESS   OF  EXPLOSIVES  43 

fulminate  detonator.  The  explosive  was  used  to  some  extent  in  Sweden. 
Early  in  the  seventies  Alfred  Nobel  bought  up  the  invention  and  took  out 
further  patents  in  connexion  with  it,  but  great  difficulties  were  experienced 
in  consequence  of  the  very  hygroscopic  nature  of  ammonium  nitrate.  Soon 
after  this  Nobel  invented  blasting  gelatine,  and  he  did  not  take  much  active 
interest  in  ammonium  nitrate  explosives  for  some  time. 

In  1871  Dr.  Hermann  Sprengel,  F.R.S.,  the  celebrated  inventor  of  the  Sprengel 
mercury  vacuum  pump,  took  out  patents  for  a  whole  series  of  mining 
explosives  to  be  made  by  mixing  an  oxidizing  substance  with  a  combustible 
one  x  "in  such  proportions  that  their  mutual  oxidation  and  de-oxidation 
should  be  theoretically  complete."  The  essential  feature  was  that  the  two 
constituents  were  to  be  mixed  together  on  the  spot  just  before  the  explosive 
was  required,  and  the  mixture  was  to  be  exploded  by  means  of  a  fulminate 
detonator.  As  oxidizing  agents  he  mentions  amongst  others  nitric  acid  and 
chlorate  of  potash  ;  as  combustibles,  a  very  large  number  of  substances 
including  nitro-benzene,  nitro-naphthalene,  carbon  bisulphide,  petroleum, 
picric  acid.  Liquid  nitric  acid  is  a  most  objectionable  material  to  handle, 
nevertheless  several  inventors  have  taken  out  patents  for  Sprengel  explosives 
containing  nitric  acid  either  enclosed  in  glass  tubes  or  absorbed  in  fossil  flour 
or  other  similar  material.2  Needless  to  say,  they  have  never  found  favour. 
In  addition  to  its  other  disadvantage  there  is  the  serious  danger  that  the 
nitric  acid  may  come  in  contact  with  the  detonator  and  cause  a  premature 
explosion.     This  actually  happened  in  1884  to  the  inventor  Punshon. 

Sprengel  explosives  consisting  of  chlorate  of  potash  and  a  liquid  combus- 
tible material  have,  however,  been  used  to  a  considerable  extent.  The  Ameri- 
can, S.  R.  Divine,  took  out  a  patent  in  1880  for  mixtures  of  this  sort  and 
several  English  patents  in  the  following  years.3  One  of  these  mixtures,  under 
the  name  of  Rackarock,  was  used  on  October  10,  1885,  for  the  great  blasting 
operation  of  Hell  Gate  in  New  York  Harbour.  On  this  occasion  240,399  lb. 
of  Rackarock  were  used  together  with  42,331  lb.  of  dynamite. 

There  are  considerable  advantages  in  transporting  separately  two  such 
inert  substances  as  nitro-benzene  and  chlorate  of  potash,  but  against  this 
must  be  put  the  difficulty  and  inconvenience  of  mixing  the  constitutents  in 
the  right  proportions  on  the  spot.  If  made  up  beforehand  the  cartridges 
are  dangerously  sensitive  and  become  more  so  on  keeping.  Under  the  English 
Explosives  Act  this  mixing  is  considered  to  constitute  the  manufacture  of 
an  explosive,  and  consequently  may  only  be  carried  out  in  a  duly  licensed 

1  Brit.  Pats.  Nos.  921  and  2042  of  1871.  Jour.  Cliem.  Soc,  1873,  p.  79(5  ;  S.S.,  1907, 
p.   184. 

2  Hellhoff,  Brit.  Pats.  1315  of  1879,  1285-87  and  2775  of  1880.  Punshon,  Brit.  Pats. 
2242  of  1 880,  2428  of  1 883.     Bichel,  French  Pat,  1 7 1 . 1 09  of  1 885. 

3  Eng.  Pat.  Nos.  5584  and  5590  of  1881,  1401  of  1882,  5024-25  of  1883. 


44 


EXPLOSIVES 


factory.  Therefore  Sprengel  explosives  have  never  been  used  in  the  British 
[sles,  but  they  were  introduced  by  the  Americans  into  China  and  Siberia 
when  the  first  railways  were  built  there,  and  one  of  them  is  now  licensed  in 
[taly.1 

A  somewhal  similar  explosive  Oxyliquit,  invented  by  Linde,  consisted 
of  liquid  oxygen  absorbed  in  wadding,  charcoal,  or  other  organic  material. 
It  was  found  that  these  mixtures  would  not  detonate  readily,  sp  kieselguhr 
was  substituted  as  absorbent  with  an  addition  of  liquid  petroleum.  This 
detonated  all  right,  hut  was  more  sensitive  to  a  blow  or  spark  than  dynamite. 
It  was  verv  inconvenient  to  use.  as  the  cartridge  had  to  he  tired  within  five 
in  fifteen  minutes  of  its  preparation,  according  to  the  diameter.  The  explo- 
sive was  tried  in  L899  by  a  commission  in  Austria,  and  on  a  fairly  Large  scale 
in  the  building  of  the  Simplon  tunnel,  but  in  spite  of  the  low  cost  of  liquid 
oxygen  it  was  found  that  the  practical  difficulties  were  very  great. 

During  the  War,  however,  the  use  of  explosives  of  this  class  is  being 
encouraged  in  Germany  in  order  that  the  available  supply  of  nitrates  may  be 
used  as  far  as  possible  for  military  purposes.  The  industrial  use  of  chlorate 
explosives  is  being  extended  for  the  same  reason. 

Sprengel  also  drew  attention  to  the  fact  that  picric  acid  by  itself  could 
be  detonated  by  a  powerful  detonator  and  was  a  very  violent  explosive,  but 
no  use  was  made  of  it  in  this  way  until  many  years  later. 

The  revival  of  ammonium  nitrate  explosives  was  due  to  the  demand  for 
such  as  would  not  ignite  the  fire-damp  in  coal-mines.  Numerous  disasters 
due  to  the  explosion  of  fire-damp  led  to  the  appointment  of  commissions  in 
many  of  the  countries  of  Europe  to  impure  into  the  matter  and  propose 
remedies.  The  nature  of  the  danger  was  investigated  in  L815  by  Sir  Humphry 
Davy,  and  one  source  of  disaster  was  removed  by  the  substitution  of  the 
Davy  lamp  for  the  naked  light.  As  time  went  on  gunpowder  was  used  more 
and  more  for  breaking  the  coal,  and  after  1  870  dynamite  w  as  also  used.  Aboul 
1ST.'}  Macnab  proposed  to  insert  a  cylinder  filled  with  water  in  front  of  the 
charge.  Others  have  suggested  wet  moss,  jelly  containing  90  per  cent,  water 
and  sawdust  saturated  with  a  solution  of  alum  and  sal  ammoniac.  Bu1 
these  devices  were  found  to  lie  cumbersome  and  expensive  and  not  very 
effect  ive. 

In  ISTi).  during  the  Siege  of  Paris,  Professor  M.  Berthelot,  w  ho  had  hitherto 
devoted  himself  to  pure  science,  was  called  upon  to  give  his  city  and  country 
the  benefit  of  his  scientific  knowledge,  and  he  was  thus  led  to  study  the  sub- 
ject of  explosives  and  especially  to  consider  the  amount  of  heat  or  energy 
liberated  in  t  hi'  reactions  which  take  place,  for  he  had  been  working  at  thermo- 
chemistry for  some  years  and  was  practically  the  founder  of  this  branch  of 
science.  After  the  war  was  over  Bert  helot  "s  services  were  still  retained  by 
1  Guttmann,  Twenty   Years'  Progress,  ]>.  10. 


PROGRESS   OF   EXPLOSIVES  45 

the  State  in  connexion  with  all  matters  connected  with  explosives.  On  the 
recommendation  of  the  French  Academy  of  Sciences  lie  was  in  187G  appointed 
a  member  of  the  Committee  on  "  Pondres  et  Salpetres."  In  order  to  deal 
adequately  with  the  many  new  inventions  he  recommended  the  formation  of 
a  special  commission.  This  was  done  in  1878,  and  Berthelot  was  appointed 
president  of  the  new  "  Com  mission  des  Substances  explosives/'  a  position 
which  he  occupied  for  many  years. 

In  1877  a  commission  was  appointed  in  France  to  inquire  into  the  question 
of  ignitions  of  coal-damp.  In  the  report  which  it  made  in  1880  it  was  obliged 
to  admit  that  there  was  then  no  explosive  known  that  would  not  ignite  coal- 
damp.  An  English  Commission  which  reported  in  1886  was  forced  to  come 
to  an  equally  unsatisfactory  conclusion. 

In  1885  the  Prussian  Government  built  at  Neunkirchen  the  first  testing  Prussia, 
station  for  investigating  mining  explosives  and  adopted  a  method  of  testing, 
which  with  slight  modifications  has  been  copied  bjr  the  Governments  of  England 
and  several  other  nations.  A  long  iron  cylinder  was  filled  with  mixtures 
of  coal-damp,  coal  dust  and  air,  and  the  explosives  were  fired.  At  first  the 
explosive  was  simply  suspended  in  the  gas  mixture,  and  it  was  found  that  the 
gas  was  ignited  every  time.  Afterwards  it  was  tired  from  a  small  mortar 
without  tamping,  and  it  was  found  that  under  these  conditions  kieselguhr 
dynamite  was  safe  up  to  100  grammes,  and  gelatine  dynamite  up  to  about  80. 

It  was  now  that  ammonium  nitrate  explosives  came  to  the  fore  again, 
as  experience  showed  that  considerably  larger  charges  could  be  used  without 
igniting  the  gaseous  mixture.  Two  of  the  first  of  these  were  roburite  and 
securite.  mixtures  of  ammonium  nitrate  with  dinitro-benzene.  But  it  was 
also  found  possible  by  suitable  admixtures  so  to  alter  the  character  of  nitro- 
glycerine explosives  that  they  can  be  used  in  coal-mines  with  comparative 
safety.  In  1885  Schmidt  and  Bichel  introduced  carbonite,  a  mixture 
of  nitro-glycerine,  saltpetre  and  flour.  This  has  been  able  to  hold  its 
own  to  the  present  day  and  is  still  considered  one  of  the  best  safety  ex- 
plosives. 

In  1887  another  commission  was  appointed  in  France  to  inquire  into  the  France, 
matter.  Influenced  by  Berthelofs  work  and  theories  it  directed  its  attention 
mainly  to  the  question  of  the  heat  developed  by  an  explosive  and  the  resulting 
temperature  of  the  products.  Explosives  having  a  high  temperature  of  explo- 
sion, such  as  nitro-glycerine  (3200°),  gun-cotton  (2600°)  or  colloelion  cotton 
(2060°),  should  be  mixed  with  a  substance  having  a  low  temperature  of  explo- 
sion such  as  ammonium  nitrate  (1130°).  Three  sorts  of  safety  explosives 
were  therefore  introduced  into  France  :  Grisoutine,  a  mixture  of  ammonium 
nitrate  and  nitro-glycerine  ;  Blasting  Powder  P,  ammonium  nitrate  and 
collodion  cotton  ;  and  Grisounite,  ammonium  nitrate  and  nitro-aromatic 
compounds  such  as  nitro-naphthalene. 


46  EXPLOSIVES 

The  great  drawback  to  the  use  of  ammonium  nitrate  ir-  it-  hygroscopic 
nature,  but  the  tendency  to  absorb  water  from  the  atmosphere  ha:*  been 
overcome  to  a  great  extent  by  coating  the  grains  with  paraffin-wax  or 
other  waterproofing  material,  and  by  enclosing  the  cartridges  in  suitable 
envelo; 
nd.  In  Germany  and  England  it  has  long  been  recognized  that  the  tempera- 

tur-  -  only  one  of  the  factor-  in  making  an  expl  fe  or 

danger'  si  se  in  fieri-  mines,  and  consequently  reliance  has  been  placed 
more  upon  trials  in  testing  galleries,  which  are  intended  to  imitate  as  nearly 
-  conditions  in  a  mine.  The  North  of  England  Institute  of 
Mining  and  Mechanical  Engineers  appointed  a  Committee  in  1888  to  inquire 
into  this  matter.     Their  trial  gallery  at  Hebburn  Colliery  v    -  pleted  in 

1892,  and  after  experimenting  with  variou>  expk»ive>  until  1895  they  recom- 
mended the  use  of  several,  the  majority  of  which  were  ammonium  nitrate 
■ 
It  was  upon  the  results  obtained  by  this  Committee  that  the  Coal  Mines 
Regulation  Act  was  founded.      This  Act.  which  i:?  still  in  force,  author- 

-  the  Home  Secretary  to  prohibit  the  use  of  any  explosive  in  coal-mines. 
and  to  appoint  Inspectors  of  Explosives  to  administer  the  Act.  A  testing 
gallery  was  erected  in  Woolwich  Arsenal,  and  there  all  explosives  had  to  be 
-d  before  they  were  permitted  to  be  used  in  coal-mines  in  the  United  King- 
dom. More  recently  a  larger  testing  gallery  has  been  erected  at  Rotherham. 
whfl  can  be  carried  out  on  lines  more  nearly  approaching  those  that 

have  been  adopted  in  Germany  and  Belgium. 

In  1  991  V   A    <  *    >treet  took  out  patents  for  explosives  consisting  of  potas- 
sium chlorate  mixed  with  castor-oil  in  which  aromatic  nitro-compound>  are 
—  >lved.      The  great   sensitiveness  of  chlorate  mixture-  i.-?  thi  >>me. 

The  explosive  thus  produced  is  called  Cheddite.  and  is  used  largely  in  England, 
France,  and  Germany. 

In  1875  the  English  "Explosives  Act,"  which  has  had  such 

a  great  influence  upon  the  development  of  the  explosives  industry.  Its  form 
largely  due  to  the  late  Colonel  Sir  V.  I).  Majendie,  who  wa-  appointed 
the  first  permanent  Inspector  of  Explosives  to  administer  its  provisions.  The 
necessity  for  legislation  was  revealed  by  an  explosion  at  Messrs.  Ludlow's, 
at  Birmingham,  which  caused  the  death  of  fifty-three  persons.  Colonel 
Majendie  war-  instructed  to  report  upon  it.  Previous  to  thi>  there  had  been 
many  other  accidents  large  and  small,  including  that  of  two  powder  magazines 
on  the  banks  of  the  Thames  at  Erith.  which  killed  thirteen  people  and  did 
great  damage  to  property. 

The  Inspectors  of  Explosives  wen-  given  power  to  ii  afl  magazines 

and  factories  and  see  that  operations  are  carried  out  in  a  reasonably 
manner.     As  a  result  the  number  of  deaths  in  explosives  factor:  -een 


PROGRESS   OF  EXPLOSIVES  47 

very  greatly  reduced  in  spite  of  the  fact  that  the  number  of  people  employed 
is  several  times  as  great  : 

Average  number  killed  per  annum 
in  explosives  factories 

1868-1870  ...  .  .      43 

.      32 


1871-1874 
1878-1887 
1888-1897 
1898-1907 
1908-1914 


7-5 
5-2 
6-9 
9-0 


By  the  wise  and  tactful  manner  in  which  they  carried  out  their  duties  Colonel 
Majendie  and  his  colleagues  conferred  this  great  benefit  upon  the  employees 
in  the  explosive  factories  without  in  any  way  seriously  interfering  with  the 
development  of  the  industry.  In  fact,  the  precautions,  which  the  inspectors 
insisted  on.  have  been  advantageous  to  the  shareholders  as  well  as  to  the 
workpeople  and  the  general  public.  In  1898  Sir  Vivian  Majendie  died  in 
harness,  but  the  work  has  been  carried  on  in  the  same  spirit  by  his  successors, 
Colonel  Ford,  Captain  J.  H.  Thomson,  and  Major  A.  Cooper-Key,  and  the 
other  Inspectors  of  Explosives  working  under  them.  The  provisions  of  the 
English  Explosives  Act  of  1875  have  been  largely  adopted  in  the  legislation 
of  foreign  countries,  British  Colonies,  and  India. 

It  has  already  been  pointed  out  that  the  early  attempts  of  von  Lenk  Smokeless 
and  others  to  make  a  satisfactory  smokeless  powder  from  gun-cotton  were  pow  ers' 
unsuccessful  because  it  was  much  too  violent  in  its  effects.  The  gun-cotton 
being  in  a  state  of  fine  fibre  interspersed  with  air  spaces  the  explosion  trav- 
elled through  it  almost  instantaneously.  Black  powder,  on  the  other  hand, 
being  a  mechanical  mixture,  the  explosion  can  only  start  at  the  points  where 
the  particles  of  saltpetre  are  in  actual  contact  with  the  particles  of  sulphur 
and  charcoal,  consequently  the  time  of  explosion  is  comparatively  long. 

The  first  successful  smokeless  powder  was  that  of  Major  Schultze,  of  the  s^tze 
Prussian   Artillery.     First,    he   appears   simply   to   have   impregnated   little  pov 
grains  of  wood  with  saltpetre.1  but  afterwards  he  purified  the  wood  to  some 
extent  by  washing,  boning  and  bleaching  it,  and  then  nitrated  it,  and  purified 
the  nitrated  lignose  by  much  the  same  process  as  that  used  by  von  Lenk  for 
gun-cotton.     The   grains   thus   obtained  were  then  impregnated  with   salt- 
petre, alone  or  mixed  with  barium  nitrate.2     This  was  introduced  about  1865.  1866. 
According  to  an  analysis  published  by  Cundill  in  the  Dictionary  of  Explosives 
the  nitro-lignin  contained  more  than  20  per  cent,  of  unnitrated  lignin.     This 
and  the  different  physical  structure  of  wood  as  compared  with  cotton  made 
the   material   burn   more  slowly  in   the  gun,  and   the  rate  was   still   further 
reduced  by  the  addition  of  the  nitrates  of  potassium  and  barium.     The  explo- 

i  Sanford,  Xitro-E.rplo*irc*,   1890,  p.   173.  J   Eng.  Pat.  I I   1864. 


4-  EXPLOSIVES 

rive  was  >till  too  violent  for  rifles,  however,  but  was  found  to  be  quite  suitable 
for  shot-guns.  The  Austrian  rights  to  Schultze's  invention  were  acquired 
by  a  firm  called  Volkmann's  K.K.  priv.  Collodinfabriks  Gesellschaft,  H.  Per- 
nice  and  <•>.  Vblkmann  took  out  AustriaD  patents  in  1870  and  1*71.  which 
were  kept  secret  at  the  time,  l>ut  Guttmann  obtained  copies  of  them  and  pub- 
lished  translations  in  his  Twenty    )'<<n     /'  Explosives  (Whittaker, 

L909  Prom  these  it  is  Been  that  Vblkmann  had  made  the  further  step  of 
partly  gelatinizing  the  grains  by  treating  them  with  a  mixture  of  ether  and 
alcohol,  whereby  thr  explosion  would  be-  restrained  still  more.  Thi>  powder 
was  made  under  the  name  of  Collodin  from  L872  to  1  875,  but  then  the  Austrian 
Government  stopped  the  manufacture  on  the  ground  that  it  was  an  infringe- 
ment of  their  gunpowder  monopoly.  The  nitro-lignin  made  as  described  by 
Volkmann  must  have  been  decidedly  impure  and.  therefore,  unstable,  and 
difficulties  were  no  doubt  experienced  in  obtaining  uniform  results. 

A  company  was  formed  in  England  in  1868  to  work  Schultze's  invention, 
and  a  factory  was  established  at  Eyeworth,  in  the  New  Forest,  in  1869.  and 
thi>  after  a  time  achieved  great  Buccess  after  the  methods  had  been  altered  by 
Griffiths.  By  1881  Schultze  powder  had  become  so  popular  with  sportsmen 
«>n  account  of  the  light  recoil  and  absence  of  smoke  as  compared  with  black 
powder,  that  the  London  gun-makers  found  irksome  the  restrictions  upon  the 
quantities  they  were  allowed  to  store.  The  manufacturers  of  this  powder 
have  modified  their  methods  from  time  to  time  to  meet  the  demands  of  sports- 
men and  to  keep  abreast  of  the  general  advance  in  the  technology  of  explo- 
sives, bo  that  the  Schultze  powders  arc  -till  amongst  the  best.  In  1883 
Schultze  started  a  factory  in  partnership  with  Voltz  and  Lichtenberger  at 
Hetzbach  in  H  Bse-Darmstadt,  and  powder  is  >till  made  there  under  Schultze's 
patents.1 
e.  c.  powder  The  n,'xt  successful  Bmokeless  powder  was  invented  at  the  worl 
1882.  the  Explosives  Company  at  Stowmarket,  which  formerly  belonged  to  Thos. 

Prentice  and  Co.  It  was  protected  by  patent  No.  619,  taken  out  in  1SS2  by 
Walter  1".  Ibid  and  I>.  Johnson.  This  was  called  E.  C.  Powder  (Explosives 
<  bmpany),  and  consisted  of  nitro-cotton  mixed  with  the  nitrates  of  potassium 
and  barium  with  the  addition  of  colouring-matter  and  small  quantities  of  other 
organic  compound-.  It  was  made  into  grains  which  were  hardened  by  being 
partially  gelatinized  by  mean-  of  a  solvent,  ether-alcohol.  A  separate  com- 
pany was  formed  to  work  the  invention  and  a  factory  was  started  at  Green 
Street  Green,  near  Dartford,  in  Kent.  This  is  Mill  in  existence,  and  K  I  . 
Powder  continues  to  be  much  used. 
Gelatinized  For  use  in  rifled  fire-arms  these  powders  are  too  quick.     For  this  purpose 

powders.         ^  j1;^  ]„.,.,,  found  nectary  to  destroy  entirely  tin-  structure  of  the  original 
cellulose  by  thoroughly  gelatinizing  it.     The  first  to  produce  a  good  smokeless 
1  A.  Voigt,  HersteUung  dcr  Sprengstoffe,  i.,  p.  116, 


PROGRESS   OF  EXPLOSIVES  49 

rifle  powder  was  the  French  engineer  Vieille,  working  on  behalf  of  the  French 
Government  in  1884.  He  incorporated  the  nitro-cotton  with  ether-alcohol 
in  a,  machine  such  as  is  used  for  kneading  bread.  The  resulting  paste  was 
rolled  out  into  thin  sheets  and  cut  into  small  squares  and  dried.  The  powder 
was  called  Poudre  B,  after  General  Boulanger.  In  1889  a  gelatinized  nitro- 
cellulose flake  powder  was  introduced  in  Germany.1  In  1888  Nobel  invented 
a  powder  called  Ballistite,  consisting  of  a  nitro-cotton  of  low  nitration  gela- 
tinized with  nitro-glycerine,  and  in  the  same  year  an  English  committee 
adopted  Cordite,  a  mixture  of  highly  nitrated  gun-cotton,  nitro-glycerine  and 
vaseline  (mineral  jelly),  gelatinized  by  means  of  acetone.  A  nitro-glycerine 
powder  of  the  cordite  type  was  adopted  in  Austria-Hungary  in  1893.2 

Every  nation  now  uses  propellants  consisting  principally  of  gelatinized 
nitro-cotton  either  by  itself  or  mixed  with  nitro-glycerine.  These  gelatinized 
powders  when  suitably  ignited  in  the  gun  burn  from  the  surface  inwards, 
consequently  the  time  of  explosion  can  be  increased  by  making  the  individual 
pieces  of  explosive  bigger.  Without  altering  the  composition  powders  can  be 
produced  suitable  for  every  sort  of  rifled  fire-arm  from  a  pistol  to  a  14-inch 
gun. 

Picric  acid  has  been  used  for  a  long  time  as  a  dye,  and  was  in  fact  the  first  Picric  aci 
artificial  dye  to  be  discovered,  for  its  formation  was  observed  in  1771  by 
Woulfe  by  the  action  of  nitric  acid  on  silk.  Laurent  was  the  first  to  make 
it  in  18-43  by  the  nitration  of  phenol  and  dinitrophenol  and  to  recognize  that 
it  is  trinitrophenol.  The  fact  that  picric  acid  combines  with  metals  and  bases 
to  form  explosive  picrates  has  also  been  known  for  a  long  time,  and  when  its 
manufacture  from  phenol  had  reduced,  its  price  many  mixtures  containing 
them  were  proposed.  Picric  acid  also  was  added  to  explosives  as  a  combust- 
ible constituent.  None  of  these  mixtures  were  used  to  any  great  extent, 
however.  In  1871  Sprengel  demonstrated,  that  picric  acid  by  itself  could  be 
detonated  by  means  of  fulminate,3  but  this  also  led  to  no  practical  result 
until  E.  Turpin  in  1885  pointed  out  the  great  advantages  of  using  picric  acid 
for  filling  shell,4  in  consequence  of  its  stability,  insensitiveness  and  violence. 
This  was  adopted,  by  the  French  Government  under  the  name  of  Melinite. 
Other  high  explosives  are  mostly  too  sensitive  to  use  in  shell  :  they  are  liable  to 
explode  in  the  bore  of  the  gun  from  the  shock  of  discharge.  For  this  reason 
gunpowder  only  was  previously  used,  and  it  still  forms  the  bursting  charge 
of  shrapnel  shell  and  other  sorts  which  only  require  a  moderate  disruptive 

1  Von  Xeyman,  Jahrbuch  der  Armee  und  Marine,  Dec  1914,  N.N. .  L915,  p.  14."). 

2  Grotouski,  Mitt.  Art. -und  Oeniewesen  through  S.S.,  1914,  \).  380. 
8   Eng.    Pat.   2642  of   1871  ;    J.  Chern.  Soc,   1873,  p.   7!Hi. 

4  French  Tat.  1  C»T.",I  l'  of  Feb.  7,  188.1.  with  additions  Oct.  17.  lSS."..  and  S(>pt.  1, 
1892.     Eng.  Pat.  15,089  of  1885.     Germ.  Pat.  38,734  of  Jan.  12,  1880. 

VOL.    I.  A 


EXPLOSIVES 

power.  EHciic  acid,  however,  is  Dearly  as  insensitive  as  black  powder  and 
can  therefore  be  used  with  Bafety  for  shell.  In  fact,  it  requires  a  very  power- 
ful detonating  primer  to  ensure  complete  detonation.  With  various  modifica- 
tions picric  arid  was  adopted  in  almost  every  country  for  this  purpose.  It 
has  the  disadvantage,  however,  that  it  readily  forms  picrates  if  it  conn-  in 
contact  with  metals  or  earthy  materials,  and  these  picrates  are  much  more 

sitive  than  picric  acid.     lt>  melting  point  also  is  inconveniently  high. 

In  hi>  patents  Tin-pin  pointed  out  that  the  sensitiveness  could  be  reduced 
>till  further  by  compression,  or  l>y  mixing  the  picric  acid  with  heavy  oils  or 
with  collodion.      At  first  collodion  was  used  in  this  way.  but  later  the  acid  has 

■rally  been  used  by  itself,  either  in  <•<  mpressed  blocks  or  melted  ami 
directly  into  the  shell.  In  1  '.'1 1  the  (  ivil  ( 'oiirt  in  Pari-  granted  Turpin  100,000 
franc-  in  compensation  because  he  hail  not  Keen  permitted  to  utilize  his  inven- 
tion to  his  own  profit.1  In  1888  picric  acid  was  adopted  by  the  German 
Army  both  for  filling  shell  and  for  military  Masting,  and  about  the  same  date 
shell  wen-  tilled  in  England  with  molten  picric  acid  under  the  name  of  Lyddite. 
derived  from  Lvdd.  the  place  where  the  experiments  were  carried  out. 
Trotyl.  In  1904  the  Germans  commenced  to  use  trinitrotoluene,  otherwise  trotyl, 

instead,  a-  it  is  free  from  the  disadvantages  of  picric  acid  referred  to  above. 
This  is  now  used  very  largely  for  high  explosive  shell,  and  i>  also  often  mixed 
with  other  substances  to  form  complex  explosn 

1  See  8.8.,   1912,  p.   ^7. 


PART  II 

BLACK  POWDER 


CHAPTER  IV 

MANUFACTURE  OF  SALTPETRE 

Nitre  deposits  :  French  saltpetre  industry  :  Artificial  nitre  beds  :  English  salt- 
petre  industry  :  Formation  of  nitrates  :  Berthelot's  researches    Bacterial  action  : 
Indian    saltpetre    industry  :    Indian  refinery  :    Chili    nitrate    deposits  :      Con- 
version -  saltpetre  :  Refining  saltpetre   :  Saltpetre  from  the  atmosphere 

So  far  as  is  possible  in  the  almost  entire  absence  of  all  records,  an  account  has 
been  given  in  Chapter  I  of  the  first  discovery  of  saltpetre. 

Until  the  middle  of  the  nineteenth  century  all  saltpetre  was  obtained  by  Nitredepc 
dissolving  it  from  earth  and  deposits  in  cellars  and  caves  and  similar  places, 
where  it  had  formed  naturally.  In  Europe  there  are  very  few  localities  where 
nitrate  can  accumulate  in  the  soil  to  such  an  extent  that  a  profit  could  be 
made  bv  extracting  it.  There  is  no  prolonged  dry  season  during  which 
deposits  can  form  without  being  washed  away  again.  Consequently  salt- 
petre could  only  accumulate  in  sheltered  places,  such  as  cellars  and  stables, 
especially  those  in  which  there  was  much  nitrogenous  matter  undergoing 
decomposition.  As  it  was  of  the  utmost  importance  in  every  country  to  have 
a  sufficient  supply  of  saltpetre,  especially  in  time  of  war,  its  production  formed 
the  subject  of  royal  decrees  and  orders  at  an  early  date.  In  France,  officers  French, 
(salpetriers  commissioner)  were  appointed  in  1540  to  search  for  and  extract 
salt  petre,  and  no  doubt  the  industry  was  in  existence  some  time  before.  1  Ins 
edict  was  confirmed  and  renewed  in  1572,  and  again  whenever  France  was 
waging  a  serious  war.  The  saltpetre  workers  operated  on  the  earth  of  stables 
sheep-pens,  cattle-sheds,  cellars  and  pigeon-houses,  and  on  the  plaster  and 
rubbish  removed  when  houses  were  pulled  down.  They  had  the  nghl  to 
gather  material  everywhere,  with  scrapers  and  brushes  in  the  houses,  with 
picks  and  shovels  in  places  not  inhabited.  No  building  or  wall  could  be  pulled 
down  until  notice  had  been  given  to  the  saltpetre  workers,  who  stated  which 
parts  they  wanted  reserved.  . 

In  the  eighteenth  century  the  saltpetre  workers  in  Prance  received  many 
additional  privileges.  For  instance,  they  could  set  up  their  vate  and  other 
plant  in  public  halls,  private  courtyards  or  wherever  they  thought  ht.      I  He 

i   Berthelot,  Sur  la  Fore*   ties  Matures  explosives,   L883,  vol.  L,  p.  346  el  seq. 

53 


54  EXPLOSIVES 

local  authorities  had  to  supply  the  \\ 1  required  for  heating,  and  provide 

te  for  transporting  the  plant  and  the  Baltpetre  to  the  refinery.     As  a  rule 
each  locality  was  visited  once  every  three  y< 
Ttiflciai  Saltpetre  was  also  obtained  from  artificial  nitre-beds,  consisting  of  earth 

itre  beds. 

mixed  with  animal  and  vegetable  matters,  ashes,  refuse  of  buildings,  lime  and 

marl.  This  was  all  placed  in  a  lam*-  barn,  and  collected  in  heaps  mixed  with 
twigs  and  intersected  with  holes  to  allow  access  "f  tin-  air.  It  was  turned 
:  also  from  time  to  time  and  watered  with  urine.  Nitrate  gradually  formed 
in  the  mass  and  was  extracted  with  water.  There  were  many  modifications 
of  this  process  adopted  in  different  pi. 

[n  the  reign  of  Louis  XIII  (1610  to  1643)  the  annual  crop  of  Baltpetre 
amounted  to  3,600,000  lb.,  but  it  gradually  diminished  in  the  eighteenth 
century  largely  on  account  of  the  strong  objection  the  people  naturally  had 
to  the  presence  of  Baltpetre  workers  in  their  houses  and  domains.  In  1T7."» 
the  quantity  had  fallen  to  1,800,000  lb.,  and  half  the  annual  requirement  was 
imported  from  India.  If  it  had  not  been  for  the  many  privileges  the  nitrate 
workers  enjoyed,  the  home  product  could  not  have  competed  at  all  with  that 
imported  from  India.  In  1789,  the  year  of  the  fall  of  the  Bastille,  a  great  effort 
-  made,  however,  to  revive  the  industry,  and  3,000,000  lb.  were  obtained. 
In  1791,  however,  the  National  Assembly  proposed  t<»  abolish  the  privileges 
of  the  saltpetre  worker-,  but  war  broke  out.  the  harbours  of  Prance  were 
blockaded,  ami  it  became  necessary  to  produce  in  the  country  all  the  saltpetre 
for  the  powder  required.  The  recent  increase  of  chemical  knowledge  and  the 
hearty  co-operation  of  the  greater  part  of  the  population  made  it  possible  to 
produce  L 6,000,000  lb.  in  a  single  year,  ami  5,000,000  in  the  next.  The  whole 
organization  was  placed  under  the  control  of  the  department  of  "  Poudres 
<t  salpetres,"  which  >till  continues  to  regulate  matter-  concerning  explosives. 
Winn  peace  was  finally  re-established,  the  renewed  competition  of  Indian 
Baltpetre  dealt  a  Bevere  blow  to  the  industry  in  France,  and  in  1  840  the  bounties 
were  abolished,  but  it  struggled  <>n  until  the  exploitation  of  the  -odium  nitrate 
deposits  in  Chile  and  the  potash  deposits  in  Germany  in  the  Becond  half  of 
the  nineteenth  century  led  to  the  production  of  artificial  Baltpetre.  The 
consequent  reduction  of  price  almost  entirely  killed  the  French  Baltpetre 
industry,  and  in  l^Tu.  when  a  scientific  committee  was  engaged  in  providing 
I'  ris  with  all  stores  necessary  for  it-  defence,  Berthelol  could  find  only  one 
or  two  -mall  producers  in  Champagne. 
ngiish  salt-  Until  the  sixteenth  century  Baltpetre  seems  mostly  to  have  been  imported 

jtreindustry  jIlt,,  England,  much  of  it  coming  from  Spain,  but  in  1515  Han-  Wolf,  a  for- 
eigner, wa-  appointed  to  be  one  of  the  King's  gunpowder  maker-  in  the  Tower 
of  London  and  elsewhere  He  was  to  _ro  from  -hire  to  -hire  to  find  a  place 
where  there  i-  Btuff  to  make  Baltpetre  of,  and  "where  he  and  his  laborers 
shall   labor,  <li'_r   or   break  in  any  ground."     He  i-  to  make  compensation  to 


MANUFACTURE   OF   SALTPETRE 

its  owners.     And  in  1  "> 3 1   Thomas  a    Lee,  one   of   the  King's  gunners,  was 

appointed  principal  searcher  and  maker  of  gunpowder.1 

As  already  stated  gunpowder  was  only  manufactured  in  England  on  a 
small  scale  until  the  second  half  of  the  sixteenth  century,  when  George  Evelyn 
started  mills  on  a  comparatively  large  scale.  Consequently  there  was  little 
difficulty  before  that  time  in  obtaining  sufficient  saltpetre,  but  then  it  became 
necessary  to  grant  the  saltpetre  men  special  privileges  for  digging  up  the  Moors 
of  stables,  dovecots  and  even  private  dwellings,  and  the  kingdom  was  divided 
into  a  number  of  areas  in  which  the  collection  and  working  of  the  saltpetre 
was  assigned  to  various  people.  In  1561  Queen  Elizabeth  granted  Gerard 
Honrick.  a  Dutchman.  £500  (or  £300)  for  teaching  two  of  her  subjects  how 
to  make  saltpetre.-  In  1588  she  granted  a  monopoly  for  gathering  and  work- 
ing saltpetre  to  George  Evelyn.  Richard  Hills  and  John  Evelyn.  The  monopoly 
extended  over  the  whole  of  the  South  of  England  and  the  Midland.-,  except 
the  City  of  London  and  two  miles  outside  it.  In  1596  Robert  Evelyn  acquired 
the  rights  in  London  and  Westminster  from  the  licensees  there.  As  a  rule, 
however,  the  Evelyns  did  not  work  saltpetre  themselves,  but  bought  it  from 
the  saltpetre  men. 

In  the  reign  of  Charles  I  there  was  considerable  friction  between  the  salt- 
petre men  and  the  public,  but  it  was  probably  due  more  to  the  weakness  of 
the  Crown  than  to  any  real  difficulty  in  obtaining  in  England  the  quantity  of 
saltpetre  required,  viz.  2 -to  lasts  per  annum.  There  was  also  competition 
between  the  saltpetre  men  and  the  soap-boilers  for  wood  ashes,  which  were 
then  practically  the  only  source  of  potash  and  were  required  for  the  conver- 
sion of  sodium  nitrate  into  the  potassium  compound.  In  1834  the  Lords  of 
the  Admiralty  gave  orders  to  the  Governor  and  Company  of  soap-boilers  that 
the  saltpetre  men  were  to  have  the  pre-emption  of  wood  ashes,  on  the  ground 
that  saltpetre  was  a  commodity  of  such  necessary  use  for  the  King  and  public 
that  it  ought  to  be  preferred  before  the  making  of  soap.3  The  monopoly  of 
saltpetre  was  abolished  in  1641  at  the  same  time  as  the  monopoly  of  gunpowder. 
It  was  revived  for  a  time  after  the  Restoration,  but  manufacture  then  was 
on  a  considerably  larger  scale. 

The  East  India  Company,  then  in  its  infancy,  imported  Indian  saltpetre 
into  England  as  early  as  1625  and  set  up  a  powder  mill  in  Windsor  Forest, 
which,  however,  was  stopped  on  the  ground  that  it  interfered  with  the  King's 
deer.  Next  year  the  Company  received  a  license  to  erect  mills  in  Surrey. 
Kent  and  Sussex.  At  this  time  it<  importations  were  on  a  -mall  scale,  but 
when  its  charter  was  renewed  in  1  «>;»:>  it  was  stipulated  that  500  tons  of  saltpetre 
should  be  supplied  every  year  to  the  Ordnance.  Ever  since  then.  Indian  salt- 
petre has  been  used  very  largely  in  England  for  the  manufacture  of  gunpowder. 

1  Brit.  Exp.   //»/..  p.    185.  J  /-'"'/.  Exp.   /<</..  pp.  -1".  -   - 

3  Brit.  Exp.   /"/••  p.  269. 


EXPLOSIVES 


o!  Whence  come  these  large  quantities  of  nitrate-  !  The  nitrogen  of  the 
atmosphere  does  not  form  chemical  compounds  at  all  readily.  Under  the 
influence  of  lightning,  and  high  tension  electricity  generally,  small  quantities 
of  nitric  acid  are  formed  and  these  are  carried  down  by  rain  into  the  soil  and 
rendered  available  for  plant  life.     But  Lav-  -  Gilbert  in  their  ref 

at   Rothamsted  found  that  the  amount  of  nitrogen  removed  with  the 

re  than  the  total  sum  of  that  added  as  manure  and  brought  down  by 
the  rain  together  with  the  loss  of  nitrogen  from  the  -oil.  No  plants  can  grow 
without  absorbing  nitrogen  compounds  from  the  soil  :  and  when  animal 
and  vegetable  m  ion  of  the  combined  nitrogen  i>  lil  el- 

ated as  niti  g  gas,  but  in  spite  of  this  steady  Loss  there  is  no  indication  that 
tin-  surface  <>f  the  earth  a-  a  whole  i-  becoming  poorer  in  combined  nitrogen, 
helot  investigated  this  matter  about  1876  and  discovered  that  nitrogen 
and  oxygen  also  combined  under  the  influence  of  electricity  of  quite  low 
rion,  -urh  as  that  yielded  by  two  or  three  electric  cells,  although  only  very 
-lowly,  and  moreover  that  in  the  presence  of  carbohydrates  such  a-  dextrine 
the  combination  was  considerably  more  rapid.1  Although  the  quantities 
thus  obtained  in  -mall  laboratory  experiments  only  amounted  to  a  few  milli- 
gramme- in  -everal  month-,  yet.  a-  there  are  always  differences  of  potential  of 
this  order  over  the  whole  surface  of  the  globe  between  the  earth  and  the  air 
above  it.  he  considered  that  this  phenomenon  wa-  sufficient  to  account  for 
all  the  nitrate-  and  other  compounds  of  nitrogen  that  are  formed. 

Since  then,  however,  it  ha-  been  found  that  this  i-  by  no  means  the  only 
*  the  formation  of  nitrogen  compounds  from  the  nitrogen  of  the  al 
sphere.     There  are  bacteria  in  the  -oil.  which  can  take  up  nitrogen  from  the 
air  and  cause  it  to  combine  with  other  elements  to  form  nitrate.-  and  more 
;l.-x  bodies  such  a-  albuminoid-.     Some  of  these,  such  a-  Azobacterium 
<  hroococcui:  rinck,  can  live  and  act  freely  in  the  -oil  ;   other-  -eem  only 

to  exist  in  the  nodules  that  are  found  on  the  roots  of  certai]  -  ts  oi  plants. 
B  terium  Radicicola  i-  perhaps  the  most  important  of  these  :  it  is  found 
on  the  root-  of  tin-  leguminosae  (beans,  peas),  and  renders  it  possible  for  these 
crops  to  grow  on  otherwise  sterile  -oil.  which  afterward-  i-  able  to  -upport 
other  crops.  8  other  plants  such  a-  the  alder  tree  have  -imilar  nodules 
on  their  root-.     There  are  eria  also,   which  convert  nil 

into  nitrite-,  others  carry  out  the  reverse  change,  other-  again  liberate  nitro- 
gen from  nitrates  or  nitrite-,  and  several  <>f  the-.-  actions  may  be  going  on 
simultaneously  in  the  -oil. 

I  action  proceeds  most  rapidly  in   a  warm  moist  climate  like  that 
of  Bengal.     The  accumulation  of  nitrate  to  such  an  extent,  that  it  can  readily 
be  collected  in  large  quantities,  also  requires  that  there  -hall  be  regula 
of  the  year  when  little  or  no  rain  fall-.     In  this  respect    !'-•  ogal  and  most  other 

1  >>>>:{.  vol.  i.,  chap.  \i. 


MANUFACTURE   OF   SALTPETRE  57 

parts  of  India  satisfy  the  conditions.  It  Mas  found  by  Leather  that  at  Pusa 
in  Behar  the  nitrification  takes  place  mostly  in  the  top  6  or  12  inches  of  soil 
and  principally  at  the  commencement  of  the  rainy  season.  There  is  more 
nitrate  in  fallow  soil  than  in  that  that  is  covered  with  crops.  The  mean 
quantity  that  was  washed  out  of  the  soil  into  the  drain  gauges  was  70  lb.  of 
nitric  nitrogen  per  acre  from  fallow  soil  and  13  lb.  from  cropped  soil.1  Head- 
den  has  found  that  in  Colorado  soils  are  often  rendered  sterile  by  the  presence 
of  too  much  saltpetre,  which  at  times  amounts  to  <>  per  cent,  of  the  soil.  It 
is  formed  by  azobacter.- 

Bihar  is  the  principal  seat  of  the  saltpetre  industry  in  India,  but  consider-  Indian  salt- 
able  quantities  also  come  from  the  United  Provinces  and  the  Punjab,  and  Petre.mdustl 
smaller  amounts  from  other  parts  of  India  and  from  Burma.  Except  what 
is  consumed  in  the  country,  the  greater  part  is  exported  from  Calcutta.  Fifty 
or  sixty  years  ago.  the  average  quantity  exported  was  over  30,000  tons  per 
annum,  now  it  is  18.000  to  20.000.  In  the  places  where  the  nitrous  earth 
is  collected  the  natural  vegetation  is  scant,  as  the  soil  in  many  cases  is  too  Bait 
for  crops  to  grow  even  during  the  rains.  It  is  obtained  in  and  around  existing 
village  sites  and  on  the  mud  walls  of  houses  and  cow-sheds.  In  the  rainy 
season,  lasting  from  June  to  October,  the  process  of  nitrification  goes  on  in  the 
warm  moist  soil,  assisted  by  the  addition  of  nitrogenous  refuse.  The  follow- 
ing account  by  R.  W.  Bingham  :!  gives  a  clear  picture  of  the  industry  in  the 
last   century  : 

*  It  is  all  made  by  a  peculiar  caste  called  *  nuniah."  and.  so  far  as  my  experi- 
ence shows,  is  principally  in  the  hands  of  ...  '  mahajuns.'  who  make  yearly 
advances,  charging  12  per  cent,  for  the  same.  The  *  nuniahs  '  are  a  tolerably 
safe  class,  compared  with  the  ordinary  '  riot  '  (peasant),  to  deal  with,  and  pay 
the  "  zemindars  '  (landowners)  a  comparatively  large  price  (if  measured  by 
the  "  bigah  ')  for  the  old  walls  and  old  sites  in  which  they  revel.  The  supply 
of  saltpetre  from  these  old  sites  appears  to  be  practically  inexhaustible  :  for 
we  find  the  '  nuniah  "  very  busy  making  up  his  piles  just  after  the  setting  in 
of  the  rains.  This  earth  he  exposes  to  the  smi  and  rain,  and  takes  care,  by 
erecting  walls,  etc..  that  the  precious  stuff  is  not  wasted  away.  A  casual 
visitor  would  not  be  able  to  understand  what  he  is  after,  but  when  the  hot 
suns  of  April,  May  and  June  come  on.  then  himself  and  his  family  boil  merrily 
away,  and  eliminate  saltpetre  and  salt  from  this  apparently  useless  soil.  Then 
the  "  mahajan  '  is  on  the  look-out  and  secures  the  saltpetre  as  it  i>  made,  and 
carries  it  to  his  own  refinery  for  final  manipulation  :    while  the  salt  which  is 

1  J.   W.    Leather,   Mini.   l)tj>.   Agr.    in   India,  vol.   ii.,   no.   2,   .Ian.    L912. 

2  \Y.    P.   Headden,   Colorado   Agr.   Col.    Expl.    Station.    Bulletins    155,    160,    through 
Nature,  1911,  p.  3(34.     J.  Ind.  Eng.  Chem.,  1914,  p.  586. 

3  Jour.  Agricultural  and  Horticultural  Soc.  xii.,  p.  107.  old   series  :    Diet.   Economic 
Products  of   India.   S.    686,   vol.    vi.    part    ii.   p.    4.'5T. 


EXPLOSIVES 


always  bitter,  and  I  should  >ay  unwholesome,  under  the  name  of  '  khari  nimuk  ' 
-  -  Id  to  the  lowest  classes  of  the  community  at  a  cheap  rate.     The  bos 
must  be  a  profitable  one.  as  the  large  bankers  of  Ghazipore.  Patna  and  Benares 
are  always  ready  to  go  into  the  trade,  and  to  advance  money  i  able 

middlemen.  .  .  .     Sometimes  these  men  experience  considerable  trouble  in 
recovering:  their  advances,  but  in  that   case  they  quietly  walk  off  with  the 


IB    I  : 


bollocks  of  the  '  nuniah  "  who  .  .  .  never  dreams  of  maki   .         mplaint,  but 
or  borrows  from  his  comrades  and  friends  till  he  has  got  money  enough  to 

release  them  by  pa\     _         k  principal  and  interest  ;    well  knowing  that  he 
will  set  no  more  advances,  and  will,  besides,  be  put  out  of  caste  by  his  c 
mate-  if  he  does  not,  at  all  event-,  pay  the  original  advance.     If.  on  the  con- 
trary, he  makes  more  -altpetre  than  will  cover  his  advance,  and  he  hae 
particular  ceremony  going  on.  he  will  clandestinely  sell  his  partially  refined 
Baltpetre  to  other  petty  pare!  -       Irnnk  while  the  money  lasts,  and 


.MANUFACTURE    OF   SALTPETRE 


59 


ask  contemptuously,  '  What,  am  I  a  poor  man  that  I  should  work  ?  '  The 
trade  is  too  hazardous  a  one,  and  the  petty  advances  spread  over  too  wide 
an  extent  of  country,  to  make  it  worth  the  while  of  Europeans  with  capital 
to  attend  to  ;  in  consequence  it  is  almost  wholly  in  the  hands  of  the  large 
houses  above  named  (who  are  connected  with  Calcutta  native  firms,  and  Mho 
in  turn  have  their  small  branches  in  every  petty  town  in  the  district)." 

The  industry  is  conducted  on  the  same  lines  now  as  then,  except  that  it 


¥ig.   4.     Evaporating  Liquor  from  Percolator. 

is  not  as  remunerative  as  it  used  to  be.  Hooper  x  made  analysts  of  a  large 
number  of  samples  of  the  earth  collected  by  the  "  nuniahs  "  :  the  amount  of 
nitrates  in  them  varied  from  1  to  27  per  cent.,  but  as  a  general  rule  they  con- 
tain 3  to  5  per  cent.,  also  several  per  cent,  of  sodium  chloride  and  Bulphate.  A 
description  of  the  process  of  extraction  has  been  given  by  Leather  and  Mukcrji.'- 

1  Agricultural  Ledger,   1905,  Xo.   3. 

-  Bulletin  No.  24  of  the  Agricultural  Research  Institute.  Pusa,  1911  ;   S.8.  1912,  110 
and   130. 


00 


KXI'LOSIVKS 


The  "  niiiiiah  '"  builds  an  earthen  charifeer  called  the  "  kuria  "  or  "  kothi  "' 
with  wet  mud,  which  is  allowed  to  dry.  This  chamber  (*ee  Fig.  3)  has  either 
circular  walls  some  5  or  <i  feel  in  diameter,  or  oblong  Malls,  and  a  floor  which 
alopee  slightly  from  hark  to  front.  In  the  front  wall  is  a  hole  at  the  level  of 
the  bed,  which  allows  the  nitrate  liquor  to  drain  away  into  a  pot.  Above  the 
bottom  of  this  earthen  chamber  a  false  bottom  is  laid,  consisting  of  bamboos 

and  matting  placed  on  a  few  Loose  brick-.  The  nitrate  earth  i-  filled  in  on 
this  with  greal  care.  Stones,  etc..  are  removed  from  it  as  far  as  possible,  and 
it  i-  put  in  slightly  moist  and  trodden  down  so  as  to  leave  no  channels,  through 
which  the  water  would  run  too  rapidly.  Wood  ashes  are  generally  mixed 
with  the  earth,  so  that  the  potash  in  them  may  convert  into  saltpetre  the 
nitrates  of  lime  and  magnesia.  A  small  piece  of  matting  is  placed  over  the 
top  of  t  lie  earth  and  water  is  poured  on  cautiously.  The  liquor  that  percolates 
through  first  i-  fairly  strong  :  it  is  transferred  to  shallow  earthenware  or  Iron 
basins  and  evaporated  down  (Fig.  4)  by  means  of  a  fire  of  wood,  leaves  or 
twigs,  or  in  the  Punjab  to  shallow  masonry  trays  in  which  the  concentration 
takes  place  through  the  action  of  the  very  dry  ail1  and  the  heat  of  the  sun. 
The  weak  liquor  that    percolates  through   afterwards,  is  thrown  on   to  a  heap 

of  already  extracted  earth,  where  it  evaporates:  this  earth  is  afterwards 
extracted  again.  The  strong  liquor  is  boiled  down  until  crystals  begin  to 
appear,  and  then  is  allowed  to  cool;  the  crystals  are  then  fished  out.  fresh 
liquor  i-  added  to  the  mother  liquor  and  the  concentration  is  carried  out  as 
before.  The  composition  of  the  crude  saltpetre  thus  produced  varies  con- 
siderably. Hooper  gives  the  analysis  of  fifty-five  samples,  and  of  these  the 
following  have  been  selected  by   Leather  as  being  typical  : 


Farukhabad 

( >kara 

Mozaf 

Burhan 

1 

in 

1 

III 

ferpore        pure 

Potassium  nitrate    . 

Calcium  nitrate 

Magnesium  nitrate. 

Sodium  chloride 

Sodium  sulphate 

Insoluble  matter 

Water    ..... 

66-07 

,"•:,. 
21-84 

3-65 

•90 

5-00 

44-!»L> 

4-80 

36-38 

10-00 

L-20 

3-70 

53-00 
2-60 

34-22 
3-88 
L-10 
5-20 

26'86 

12-24 
34-80 
1  1-20 
1-40 
13-50 

49-36 
3-28 

7-44 

Ili-SL' 

14-lill 
1-50 
7-00 

68-40 
2-60 
2-12 

17-98 

:i-4ii 
1-70 
3-80 

inn 

Kin            inn 

Kin 

Kill 

L00 

No  attempt   is  made  to  separate  the  sodium  chloride  at   this  stage  because 


MANUFACTURE   OF   SALTPETRE 


61 


there  is  an  excise  duty  on  it.  and  the  sail  department  only  allows  the  recovery 
to  take  place  in  the  refineries,  where  a  proper  control  can  be  kept.  Some  of 
the  crude  saltpetre  is  used  as  manure,  but  the  greater  part  goes  to  the  refinery. 

In  the  refinery  the  processes  are  very  similar  to  those  carried  out  by  the  Indian 
••  nuniah."  There  is  always  a  large  heap  of  saltpetre  earth,  which  is  worked 
over  and  over  again,  the  weak  liquors  being  always  thrown  on  to  it.  This  is 
extracted  in  "  kothias,"  but  the  strong  liquors  are  not  evaporated  down  by 
themselves  ;  crude  saltpetre  is  dissolved  in  them  at  the  boiling-point.  The 
quantity  added  is  such  that  the  potassium  nitrate  is  all  dissolved  to  form  a 
boiling  saturated  solution,  whereas  the  greater  part  of  the  sodium  chloride 
remains  undissolved  (see  Table  of  Solubilities  on  p.  63)  together  with  the 
insoluble  matter.  The  hot  liquid  is  allowed  to  settle  for  a  little  while,  and 
then  inn  into  wooden  vats  where  it  is  allowed  to  cool  slowly  and  deposit 
crystals  of  potassium  nitrate.  The  residue  in  the  dissolving  tank  is  washed 
with  water  to  recover  the  saltpetre  in  it,  and  the  common  salt  may  be  purified 
by  dissolving  it  in  weak  nitre  liquor,  decanting  off  and  evaporating  down. 
The  insoluble  matter  and  all  weak  liquors  are  added  to  the  heap  of  earth, 
which  steadily  grows  from  year  to  year.  The  mother  liquor  from  the  crystalliza- 
tion of  the  saltpetre  is  also  added  to  it  after  it  has  been  used  three  or  four 
times,  as  it  is  then  too  impure. 

The  refined  saltpetre  is  in  large  crystals  of  a  brownish  colour.  To  purify 
it  further  and  improve  the  colour  it  is  sometimes  subjected  to  a  washing 
process  :  it  is  put  in  sacks  over  wooden  tubs  and  cold  water  is  poured  through 
it.  This  of  course  dissolves  some  of  the  potassium  nitrate  as  well  as  the 
impurities,  and  is  consequently  returned  to  the  refinery  process.  Leather 
and  Mukerji  give  the  following  analyses  of  refined  saltpetre  before  and  after 
washing  : 


Burhanpura 

Savan 

Bakramau 

Un- 
washed 

Washed 

Un- 
washed 

Washed 

Un- 
washed 

Washed 

Potassium  nitrate    . 

Potassium  sulphate 

Sodium  sulphate 

Potassium  chloride. 

Sodium  chloride 

Sand 

90-70 

•91 

5-40 

94-91 

•03 

3-12 

•20 

81-98 
5-44 

2-59 
7-05 

•20 

91  •;..-)       88-63 
•93             -15 

l>-;,1          6-06 
1-68             •(>" 
•35 

94-70 

•1.-. 

2-67 
•10 

Leather  has  designed  a  simple  plant  on  more  up-to-date  lines  to  carry 
out  the  refining  process,  and  is  endeavouring  to  get  the  Indian  refiners  to  take 
it  up.     This  consists  of  a  dissolving  vessel  provided  with  a  stirrer,  a  filter  in 


62 


EXPLOSIVES 


which  the  liquor  is  rapidly  filtered  at  a  high  temperature,  and  a  series  of 
cooler>  in  which  the  Baltpetre  is  caused  to  crystallize  rapidly.  The  crystals 
are  then  freed  as  far  as  possible  from  the  mother  liquor  in  a  centrifugal 
machine.     The  Baltpetre  produced  has  a  purity  of  90  to  93  per  cent. 

The  plain  of  Tamarngal  in  Chili  is  even  more  favourably  situated  than 
Bihar  or  Bengal.  It  lies  between  the  Andes  and  the  comparatively  low  Coast 
Hills  at  a  height  of  about  3000  feet  above  the  sea  within  the  tropics.  As  a 
rule  there  is  very  little  rain  there,  but  about  once  in  six  or  seven  years  the 
plain,  which  is  about  4.">  miles  wide,  is  flooded.  The  plain  slopes  gently 
towards  the  <  oast  Hills  and  as  there  is  no  outlet  for  the  water,  it  collects  there 
and  evaporates,  and  all  the  nitrate  it  has  dissolved  from  the  entire  plain 
is  deposited  in  a  comparatively  narrow  area.  The  entire  product  of  the 
bacterial  action  upon  many  hundreds  of  square  miles  for  many  centuries  is 
found  in  the  Chili  nitrate  beds.  As  the  soil  contains  sodium  compounds 
and  comparatively  little  potassium,  it  is  principally  sodium  nitrate  that  has 
been  desposited.1 

The  following  gives  the  results  of  analysis  of  commercial  Chili  nitrate  : 


Sodium  nitrate 

.      94-20 

Potassium  nitrate 

1-51 

Sodium  chloride 

1-06 

Sodium  iodate  . 

0-01 

Potassium  chlorate    . 

0-26 

Magnesium  sulphate  . 

0-26 

•i  chloride    . 

0-32 

Calcium  sulphate 

0-07 

ible 

0-16 

Water 

2-15 

100 


During  the  Crimean  War  (1854-1855),  the  demand  for  saltpetre  was  so 
great  that  the  existing  sources  of  supply  in  Europe  and  India  did  not  suffice, 
and  considerable  quantities  were  made  from  Chili  nitrate,  which  had  been 
supplied  to  Europe  in  constantly  increasing  quantities  since  1830.  The 
salt  beds  at  Stassfurt,  however,  did  not  commence  to  yield  potassium  chloride 
(Carnallite)  until  about  1863,  therefore  other  sources  of  potash  had  to  be 
used  to  convert  the  sodium  nitrate  from  Chili  into  the  corresponding  potas- 
sium Bait.  The  only  BOUrces  of  potash  then  available  were  kelp,  and  the 
ash  of  wood.  etc.  When  the  war  was  over.  Baltpetre  prepared  in  this  way 
could  no  longer  compete  with  the  natural  product  from  India.  But  shortly 
afterwards  fresh  sources  of  potash  were  found  in  "suint,"  the  dried  sweat 
of  Bheep,  which  is  washed  from  tin-  wool,  and  in  the  cinder  of  '*  vinasse 

Newton,  J.  8oc  Chem,  Int.,  1900,  p.    •   - 


MANUFACTURE  OF  SALTPETRE 


63 


Conversion" 


(Schlenipekohle).  which  is  obtained  as  a  by-product  in  the  refining  of  beet 
sugar.  With  the  development  of  the  Stassfurt  potash  industry  these  lost 
their  importance  however. 

Large  quantities  of  potassium  nitrate  are  now  made  by  the  interaction 
of  Chili  nitrate  and  commercial  chloride  of  potash,  which  is  made  by  lixiviating  saltPetre- 
;:  camaUite,"  a  double  chloride  of  potassium  and  magnesium,  occurring  in 
immense  deposits  near  Stassfurt  in  Germany.  In  the  heated  and  concentrated 
mother  liquor  from  a  previous  operation  commercial  sodium  nitrate  (about 
95  per  cent,  purity)  and  potassium  chloride  (not  less  than  SO  per  cent,  purity) 
are  dissolved,  the  nitrate  being  in  slight  excess.  Of  the  four  salts  that  might 
be  present  in  the  solution  thus  formed,  sodium  chloride  has  the  least  solu- 
bility at  a  high  temperature  and  potassium  nitrate  the  greatest  [set  Table 
below).  At  a  low  temperature  potassium  nitrate  has  the  lowest  solubility. 
The  figures  are  of  course  for  pure  salts  dissolved  in  distilled  water,  and  the 
presence  of  other  substances  in  solution  would  alter  the  solubilities  some- 
what, but  the  figures  given  in  the  last  two  columns,  the  solubilities  of  sodium 
chloride  and  potassium  nitrate  in  water  which  is  simultaneously  saturated 
with  both  salts,  show  that  in  this  case  the  salts  have  little  effect  upon  one 
another's  solubility.  Consequently  in  the  hot  concentrated  solution  of  sodium 
nitrate  and  potassium  chloride  most  of  the  sodium  chloride  is  precipitated  out  : 
NaN03  +  KC1  =  KN03  +  NaCl 
Table  of  Solvbtlities 


Gramme  mols.  pe 

r  1000  g. 

water 

Temperature 

One  salt  only  present 

When  water  is  saturated 
with  KXO3  and  NaCl 

NaCl 

KC1            XaX03 

KXO3 

KXO3 

NaCl 

0°  c. . 

6-10 

3-70              S-54 

1-31 

1-8 

5-6 

20 

. 

6-14 

4-.3I3            10-3 

3-12 

3-4 

6-5 

40 

. 

6-24 

5-36           12-2 

6-32 

6-0 

6-4 

60 

. 

6-3(3 

6-11            14-5 

10-9 

9-9 

6-0 

80 

. 

6-53 

6-85           17-4 

16-7 

16-5 

6-2 

100 

. 

6-75 

7-60           20-9 

24-3 

28-0 

6-9 

120 

• 

6-84 

8-43           251 

38-9 

38-0 

7-2 

Calculated  from  figures  in  Seidell's  Solubilities  of  Inorganic  and  Organic  Substances, 
1907.  A  "  gramme- mo  1."  is  the  molecular  weight  of  a  substance  in  grammes.  To  find 
tin-  actual  weight  of  the  salts  dissolved  by  1000  parts  of  water,  multiply  the  above  figures 
by  the  corresponding  molecular  weights  :  for  NaCl  58'5,  KC1  7-4- ti.  XaXO,  85*1,  KX03 
101-1. 


64 


EXPLOSIVES 


The  solubilities  o£  these  different  salts  in  the  presence  of  one  another  have  recently 
been  investigated  by  J.  W.  Leather  and  J.  X.  Mukerji,  whose  results  do  nol  differ  very 
greatly  from  the  above.  At  temperatures  below  :>'»  C,  however,  they  found  that  a 
Bmall  proportion  of  KC1  is  formed  in  a  solution  saturated  with  KNO,  and  Nad,  and  a 
oorresponding  amount  of  solid  Ni  NO  -  deposited.  At  temperatures  above  30  C.  on 
the  other  hand  K('l  is  deposited  and  NaNO,  formed  in  solution,  and  as  the  temperature 
the  quantities  of  these  salts  increase  rapidly.1 

The  liquid  ia  boiled  for  half  an  hour  to  complete  the  reaction  as  far  as 
possible,  then  it  is  run  through  a  filter  into  shallow  cooling  tanks  ;  some  more 
water  may  now  be  added  with  advantage-  to  prevent  Bodium  chloride  separating 
out  with  the  potassium  nitrate. 

The  solution  is  kept  stirred  whilst  it  cools,  bo  that  the  potassium  nitrate 


Fig.  5,     Plant   for  Refining  Saltpetre  at   Waltham  Abbey. 

may  separate  in  small  crystals,  which  do  not  contain  so  much  mother  liquor 
as  large  ones.  The  crystals  arc  drained  and  then  washed  with  the  liquors 
from  the  next  crystallization.  This  ia  best  done  in  a  centrifugal  machine,  as 
the  quantity  of  washing  liquor  is  thereby  reduced  to  a  minimum. 

The  crude  saltpetre  thus  obtained  still  contain-  several  per  cent,  of  sodium 
chloride  and  about  a  half  per  cent,  of  magnesium  chloride.  It  is  purified  by 
dissolving  in  the  washings  of  the  purified  salt,  allowing  it  to  crystallize,  and 
washing  with  water,  whereby  the  percentage  of  chloride  is  reduced  to  005 
per  cent.  or  leas,  and  the  material  is  rendered  practically  free  from  all  other 
impurities.     Finally  it  is  dried. 

The  sodium  chloride  formed  in  the  conversion  is  washed  on  the  filter  with 
liquors  containing  gradually  diminishing  amounts  of  nitrate,  until  the  solid 
contains  only  0-8  percent,  or  less.     This  "■  -alt] ict re  salt  **  then  contains  about 

1  Mem.  of  Dipt.  <■;  Agriculttm    in   India,  Chemical  Series,  voL  in..  No.  7.   1(.M4. 


MANUFACTURE  OF  SALTPETRE  65 

98  per  cent,  of  sodium  chloride  in  the  dry  state.  It  is  unsuitable  for  the 
manufacture  of  hydrochloric  acid,  because  this  would  be  contaminated  with 
nitrous  compounds,  and  moreover  the  plant  would  be  strongly  attacked. 
It  is  therefore  either  sold  to  farmers  to  put  on  the  land  or  used  in  copper 
extraction  or  other  metallurgical  processes. 

"  Artificial  "  or  "  conversion  "  saltpetre  made  as  above,  is  usually  supplied 
by  the  chemical  works  to  the  explosives  factory  in  such  a  state  of  purity  that 
no  further  purification  is  necessary.  Natural  saltpetre  from  India  on  the 
other  hand  always  contains  a  considerable  amount  of  impurity  and  requires 
to  be  refined  before  use. 

Although  the  quantity  of  black  powder  made  is  still  very  considerable, 
it  is  not  nearly  so  large  as  it  was  twenty  years  ago.  The  black  powder  factories 
now  being  worked  were  all  in  existence  at  that  time,  and  they  mostly  have 
large  saltpetre  refineries  attached,  which  more  than  suffice  to  refine  all  the 
material  that  they  require.  It  has  not  been  found  worth  while  to  recon- 
struct the  refineries,  as  they  are  still  capable  of  turning  out  saltpetre  of  good 
quality.  It  would  nowadays  be  possible,  however,  to  erect  up-to-date  plant 
that  would  save  much  space  and  some  fuel  and  labour. 

At  Waltham  Abbey,  as  at  some  other  English  powder  factories,  Indian  Refining 
saltpetre  is  used  exclusively.     The   total   quantity  imported  into   England 
every  year  is.  however,  only  10,000  tons  and  the  total  consumption  for  making 
powder,  etc.,  several  times   that    amount.     The  balance   is   made    up    with 
"  conversion  "  saltpetre. 

The  method  of  refining  still  followed  at  Waltham  Abbey  is  as  follows  :  Waithar 
The  crude  or  "  grough  "  saltpetre  is  dissolved  up  in  a  large  iron  copper,  A 
(Fig.  5),  which  has  a  capacity  of  500  gallons,  and  is  fitted  with  a  perforated 
false  bottom  which  prevents  the  saltpetre  adhering  to  the  vessel.  For  each 
charge,  about  25  cwts.  of  grough  saltpetre  are  taken,  and  5  cwts.  of  crystals 
recovered  from  liquors,  and  5  cwts.  of  crystals  left  in  the  crystallizing  cisterns. 
This  is  all  dissolved  in  about  280  gallons  of  the  washings  of  the  purified  salt- 
petre, which  also  contains  a  considerable  amount  of  the  salt.  The  fire  is  lit 
under  the  copper,  and  in  about  two  hours  the  saltpetre  is  dissolved  and  the 
liquid  boiling.  Just  before  it  boils  a  thick  scum  rises  to  the  surface  consisting 
mostly  of  impurities.  This  is  skimmed  off  and  the  false  bottom  is  removed, 
and  cold  water  is  added  from  time  to  time  to  induce  fresh  scum  to  form,  if  it 
will.  The  fire  is  then  withdrawn  and  the  liquid  is  allowed  to  settle  for  two 
hours.  Then  a  hand  pump  is  lowered  into  the  copper  and  the  liquid  is  pumped 
into  filters  B,  where  it  passes  through  linen  cloth.  From  here  it  runs  to 
shallow  copper  crystallizing  troughs  C.  As  it  cools  down,  the  liquid  is  kept 
stirred  by  a  workman  in  order  to  make  the  saltpetre  separate  in  small  crystals, 
and  the  saltpetre  "  flour  "  as  it  forms  is  drawn  up  on  to  an  inclined  draining 
platform  D,  and  from  there  is  passed  to  a  washing  vat  E.  After  the  tempera* 
vol.  r.  5 


(56  EXPLOSIVES 

ture  has  fatten  to  about  32  I  90  F.)  the  solution  is  no  longer  stirred  and  any 
crystals  that  form  after  thai  are  treated  as  grough  nitre 

The  washing  vat  E  is  aboul  «'•  feel  long,  by  4  feel  wide.  l.\  :;  feel  6  inches 
deep,  and  is  fitted  with  a  false  bottom  made  of  wood  with  small  holes  bored 
in  it.  Below  the  false  bottom  is  a  plug  which  can  be  removed  to  allow  the 
washings  to  flow  away.  First  the  charge  is  washed  with  To  gallons  of  water 
sprinkled  over  it  by  means  of  a  rose,  the  plug  being  left  out  bo  thai  the  washings 
can  drain  away  to  a  liquor  tank  F.  After  draining  half  an  hour  the  plug 
is  inserted  and  the  saltpetre  covered  with  fresh  water,  which  after  standing 
half  an  hour  is  also  allowed  to  drain  into  F.  Finally  the  sail  is  washed  by 
sprinkling  with  100  gallons  of  water,  the  plug  remaining  out.  The  saltpetre 
is  new  allowed  to  drain  all  night  and  is  then  removed  to  the  store-house  where 
it  is  allowed  to  dry  spontaneously.  In  about  .three  days  the  moisture  has 
fallen  to   3  or  5  per  cent. 

The  mother  liquors  and  other  impure  solutions  are  boiled  down  to  about 
a  quarter  of  their  original  volume.  Any  scum  or  deposit  that  forms  during 
the  boiling  should  be  removed  and  water  then  be  added.  The  solution  is 
now  filtered  and  allowed  to  crystallize.  The  crystals  are  treated  as  grough 
saltpetre  and  the  mother  liquor  returned  to  the  evaporating  pots. 

The  method-  of  refining  adopted  in  France,  Germany  and  other  countries 
are  substantially  the  Bame  as  that  at  Waltham  Abbey.  A  small  proportion 
of  size  iv-  however,  often  added  in  the  refining  copper  to  assist  the  formation 
of  scum. 

!'  tassium  nitrate  could  also  be  made  from  the  calcium  nitrate  produced 
from  atmospheric  oxygen  and  nitrogen  by  processes  such  as  that  of  Birkeland 
and  Eyde  as  carried  oul  at  Notodden,  but  the  calcium  chloride  obtained  as  a 
by-product  would  be  of  no  value.  Or  the  dilute  nitric  acid  obtained  in  the 
Birkeland-Eyde  process  could  be  treated  with  limestone  or  chalk  and  potassium 
chloride  : 

2KC1  -  2HNO,  =  2KNO     -    <  a<  1      •    CO,  +H20. 

In  this  case  the  carbonic  acid  could  be  collected  and  compress*  d  into  cylinders 
and  Bold.     Up  to  the  present,  these  methods  do  not  appear  to  have  been 
adopted,  but  nitric  acid  and  ammonium   nitrate  arc   being   made  on  a  very 
_     scale,  especially  in  Germany.1 

1  See  chap.  \iii. 


CHAPTER  V 
MANUFACTURE  OF  CHARCOAL  AND  SULPHUR 

Charcoal  :  Wood  used  :  Distillation  :  Composition  :  Brown  charcoal  :  Sulphur  • 

bicihan  sulphur  :  By-product  sulphur  :  Louisiana   sulphur  :  Refining  sulphur  : 

Properties  :  Functions  of  sulphur 

At  one  time  the  charcoal  for  black  powder  was  made  almost  exclusively  from  Woodu< 
alder-wood  but  later  other  soft  woods  were  used,  and  straw  charcoal  was  also 
introduced  for  the  brown  powders  for  heavy  ordnance.  Charcoal  from  soft 
woods  is  generally  used,  especially  for  the  better  qualities  of  gunpowder 
because  it  is  more  easy  to  ignite.  In  England  dog-wood  is  much  used,  espec- 
ially for  rapid  burning  powders  of  small  grain  ;  for  larger  powders,  alder  and 
willow.  In  Germany  alder  and  willow  are  the  principal  woods  used-  in 
Austria  alder  and  hazel ;  in  Switzerland,  hazel ;  in  France  black  alder  is  used 
tor  high  class  powders,  for  mining  powders  common  white  woods  such  as 
white  alder,  poplar,  aspen,  birch  and  hazel ;  in  Spain,  the  oleander,  yew 
willow,  hemp  stems,  and  vine  ;   in  Italy,  almost  exclusively  hemp  stems. 

Charcoal  burnt  in  heaps  or  kilns  has  not  been  used  very  largely  for  gun- 
powder since  even  the  very  earliest  days,  for  it  was  soon  found  that  to  produce 
good  powder  it  was  necessary  to  select  the  wood  carefully  and  burn  it  very 
uniformly.  It  has  therefore  been  heated  in  ovens  or  iron  vessels,  and  the 
procedure  of  the  present  day  does  not  differ  materially  from  that  of  the 
fourteenth  century. 

The  wood  should  be  cut  in  the  spring,  as  the  sap  in  it  at  that  time  of  the 
year  contains  much  less  inorganic  matter,  so  that  although  the  proportion 
of  sap  is  larger,  yet  the  percentage  of  ash  in  the  wood  is  much  smaller.  More- 
over, wood  cut  in  the  spring  is  much  more  easily  freed  from  its  bark,  which 
also  contains  a  large  proportion  of  ash.  The  wood  is  kept  at  least  eighteen 
months,  and  generally  not  less  than  three  years,  to  allow  the  sap  to  dry  out 
of  it  and  other  changes  to  take  place.  The  practice  varies  considerably  as 
regards  protecting  the  wood  from  rain  :  at  Dresden  it  is  kept  in  sheds  ;  at 
Spandau  in  the  open  ;  at  Waltham  Abbey  also  the  wood  is  kept  in  the  open, 
but  the  dog-wood  is  covered  with  thatch,  whereas  the  alder  and  willow  are 
not, 

67 


68  EXPLOSIVES 

The  wood  l-  split  if  necessary  into  pieces  about   1  inch  thick,  and  these 
are  placed  in  an  iron  cylinder  about  2  feet  in  diameter  and  :>  feet  •'•  inches 

_  This  cylinder  is  then  raised  by  means  of  suitable  tackle  and  p] 
in  a  furnace,  which  is  heated  as  uniformly  as  possible.  The  higher  the  tem- 
perature and  the  longer  the  heating,  the  lower  is  the  percentage  of  hydrogen 
and  oxygen  in  the  charcoal  and  the  greater  is  its  hardness  and  the  difficulty 
with  which  it  i-  ignited.  At  Waltham  Abbey  dog-wood  for  R.F.(i.  or  M.G.1 
powders  is  heated  4  hours  I  R  !  I  ■  -  Bh  ra  Alder  and  willow  for  R.l 
are  heated  3|  hours,  for  R.L.G.4,  P.,  and  Prism1  Black  4  hours,  for  1'-  6 
hoi.  a 

When  the  temperature  of  the  wood  attains  about  280  I  .  volatile  products 
of  decomposition  of  the  wood  come  off  plentifully.  These  could  be  condensed 
by  means  of  a  suitable  condenser,  and  worked  up  mto  acetate  of  lime  and 
1  spirit.  The  charcoal  plant  of  a  powder  mill  is,  however,  on  such  a 
small  scale  as  compared  with  the  factories  in  which  charcoal  is  produced  for 
metallurgical  pro  -     ith  recovery  of  the  by-products,  that  it  is  not  usually 

sidered  worth  while  to  do  this.  The  volatile  products  are  therefore  simply 
led  into  the  furnace  by  which  the  wood  is  being  heated,  and  so  some  expendi- 
ture of  fuel  -  -  ved.  To  enable  the  gases  and  volatile  products  to  escape 
the  cylinder  has  some  holes  bored  in  it  at  one  end.  and  the  furnace  is  provided 
with  a  pipe  to  lead  away  these  products.  When  the  carbonization  has 
eeded  far  enough,  the  flame  of  the  burning  gas  become-  blue.  The  furnace 
i-  then  opened,  the  cylinder  taken  out  by  means  of  the  tackle,  and  a  fn  sh 
cylinder  of  wood  put  in  before  the  furnace  has  had  time  to  cool.  The  cylinder 
that  has  been  taken  out  is  placed  in<ide  a  larger  cylinder,  which  has  a  closely 
fitting  lid.  and  is  there  allowed  to  cool.  It  is  necessary  that  the  cooling  should 
take  place  out  of  contact  of  the  air.  as  otherwise  the  charcoal  will  catch  fire. 
.  when  cold  it  at  fir>t  absorbs  large  quantities  of  oxygen  from  tin-  air. 
and  in  so  doing  may  become  sufficiently  hot  to  catch  fire.  Therefore  oxygen 
must  only  be  allowed  gradual  access  to  the  charcoal  :  it  should  not  be  ground 
until  a  week  after  it  has  been  burnt.  Before  use  it  i>  carefully  picked  over 
by  hand  to  remove  any  that  has  not  been  properly  burnt,  as  also  any  foreign 
matters  that  have  got  into  it.  Charcoal  intended  for  powders  for  ordnance 
should  be  jet  black  in  colour:  its  fracture  should  show  a  clear  velvet-like 
surface  :  it  should  be  light  and  sonorous  when  dropped  on  a  hard  surface, 
and  bo  soft  that  it  will  not  scratch  polished  copper.1  The  yield  of  such  char- 
coal U  29  •  30  per  cent,  of  the  dried  wood.  For  small-arms  a  more  slackly 
burnt  charcoal  can  be  used,  and  th<-  yield  may  be  as  much  a-  40  per  cent. 
Such  charcoal  has  a  reddish-brown  colour,  which  i<  perceptible  in  the  powder 
until  it   ha-  been   glazed  with   graphite. 

1  Tn    tit  S  ■      ■•    1907,  p.   10. 


MANUFACTURE  OF  CHARCOAL  AND  SULPHUR 


69 


The  composition  of  some  typical  charcoals  is  shown  in  the  Table1  below.  Compositi 
Spanish   hem})  charcoal  is  usually  burnt  in  pits  holding   h  to  1  ton.     When 
the  carbonization  has  proceeded  far  enough  the  pit  is  covered  with  a  woollen 
cloth  on  which  earth   is  placed.     This  probably  accounts  for  the  high  per- 
centage of  ash  in  the  analysis  below. 


Description 

Carbon 

Hydrogen 

Oxygen 

Ash 

From  P.  Powder,  Waltham  Abbey  . 

85-26 

2-98 

10-16 

1-60 

From  R.L.G..  Waltham  Abbey 

80-32 

3-08 

U-7.-) 

1-85 

From  R.F.(;..   Waltham  Abbey 

75-72 

3-70 

18-84 

1-74 

From  F.G.,   Waltham  Abbey    . 

77-88 

3-37 

17-60 

1  •  1  r. 

Curtis's  and   Harvey.    Sporting 

77-30 

3-7  7 

16-62 

2-25 

Curtis's  and  Harvey.  Mining    . 

83-74 

3-07 

10-4.-. 

2-74 

Spanish.  Hemp  Charcoal. 

76-29 

3-31 

14-87 

5-53 

German  Sporting  Powder.     (B.  &  S.) 

08-8 

3-7 

27-5 

Trace 

Austrian   Cannon  Powder.      (K.) 

si-:; 

2-8 

13-0 

2-3 

Austrian   Small   Arm  Powder.      (K.). 

82-6 

2-9 

12-5 

2-0 

Russian  Powder.     (F)       .... 

72-5 

2-9 

22-3 

2-3 

The  charcoal  for  brown  or  "  cocoa  "  powder  Mas  made  from  rye-straw.  Brown 
which  was  only  carbonized  very  slightly.-  It  was  heated  only  about  half  c 
an  hour,  then  taken  out  of  the  furnace.  The  carbonization  proceeded  spon- 
taneously a  little  further  and  then  the  charcoal  cooled.  The  result  was  a  soft 
charcoal  containing  a  large  percentage  of  oxygen  and  hydrogen.  In  the 
operation  of  pressing  the  powder  this  became  a  coherent  colloid  which  bound 
the  other  constituents  together  to  a  dense  impervious  mass,  which  burnt 
comparatively  slowly.  The  cocoa  powder  gave  the  best  ballistics  in  heavy 
ordnance  of  any  '*  black  "  powder  ever  produced,  but  it  has  now  been  entirely 
displaced  by  smokeless  powders. 

For  cheap  blasting  powder  and  powder  for  scaring  birds  and  supplying 
natives  of  Africa,  etc..  charcoal  of  an  inferior  quality  can  be  used. 


SULPHUR 


Sulphur  occurs  native  in  many  volcanic  districts,  especially  in  Sicily,  Sicilian 
and  until  recent  times  practically  the  whole  of  the  world's  supply  came  from  sulphur- 
there.     The  sulphur  in  Sicily  is  mixed  with  limestone,  the  ores  containing 

1  Noble  and  Abel,  Trans.  Roy.  Soc.,  1875  and  1879;  Hoble,  Artillery  and  Explosives, 
1900,  pp.  127.  12!».  "  B.  &  S."  means  analysis  by  Bunsen  and  Schischkoff,  "  K  "  by 
Karolyi.   "  F  "  by  Fedeow. 

-  Guttmann,  Manufacture,  vol.  i.,  p.  90;  Cundill  and  Thompson,  p.  21  ;  Trtatisi  mi 
Senna    Explosives,    1900,  p.   1 10 


?o  i:\i'L<»i\    - 

usually  from  -"  to  40  per  cent,  of  sulphur.     Formerly  the  sulphur  was 

by  the  wasteful  "  calcaroni  ""  process.     The  ore  was  piled  in  a  large  heap 

and  covered  over  with  moistened  ash  except  for  a  small  opening.  (  ombustion 
was  started  with  burning  wood,  but  the  combustion  of  part  of  the  sulphur 

provided  most  of  the  necessary  heat.  The  sulphur  melted  out  and  flowed 
down  on  to  a  prepared  floor.  (July  about  60  per  cent,  of  the  sulphur  in  the 
ore  was  recovered  by  this  process,  and  the  large  quantities  of  sulphur  dioxide 
set   free  were  very  injurious  to  the  suiTOunding  vegetation.     This  method 

been   largely   superseded  by  the  introduction  of  recuperative  fun 
invented  by  Gill  and  modified  by  Saiifillipo.     About  six  large  chambers 
arranged  in  a  Belies  so  that  the  hot  gases  from  one  can  be  made  to  heat  the 
next.     By  this  process  the  recovery  is  about  80  per  cent.     Attempts  I 
been  made  to  introduce  more  efficient  methods  whereby  practically  the  whole 
of  the  sulphur  could  be  recovered  by  melting  it  out  with  hot  brine  or  steam, 
or  distilling  it  with  superheated  steam.     These  methods  have  not  attained 
any  great  Buccess,  however,  the  obstacles  being  the  absence  of  any  local  supply 
of  fuel  and  the  backward  state  of  the  country.     The  sulphur  is  refined  by 
distillate -n.  the  principal  distilleries  being  situated  in  Marseilles.     Some  powder 
mills  have  small  sulphur  refineries  of  their  own.  as  at  YValtham  Abbey  for 
instance. 

Two  sorts  of  sulphur  can  be  obtained  by  distillation:  flowers  and 
stick  sulphur.  The  former  consists  of  minute  crystals,  which  have  been 
deposited  on  the  interior  surface  of  a  large  chamber  or  "dome  "'  into  which 
the  vapours  have  been  passed.  The  flowers  contain  a  small  percent  s 
of  sulphuric  acid  formed  by  the  action  of  the  air  on  the  sulphur,  and 
consequently  are  not  suitable  for  the  manufacture  of  explosivee  Mick 
sulphur,  on  the  other  hand,  is  very  pure  and  only  requires  to  be  ground. 

For  the  manufacture  of  sulphuric  acid  elementary  sulphur  is  but  little 
used  ii"\\ .  as  it  pays  better  to  roast  various  ores  in  which  it  is  combined  with 
metals,  Buch  as  copper  pyrites  and  zinc-blende,  but  it  does  not  pay  to  extract 
Bulphur  as  Buch  from  t      -  s.     A  certain  proportion  of  it  comes  on  the 

market,  however,  as  it  is  obtained  as  a  by-product  in  the  Leblanc  Boda  pro- 
TJie  sulphuric  acid  used  in  that  process  is  ultimately  converted  into 
calcium  Bulphide,  CaS,  and  for  many  years  this  accumulated  in  great  heaps 
which  were  a  public  uuisance,  no  method  being  known  by  which  it  could 
be   worked   up   except    at   a  prohibitive  cost.     Eventually  the  daue 
process  was  devised  and  perfected,  which  enabled  this  to  be  done.     Kiln  _ 
is  passed  over  the  "soda-waste,"  converting  it  into  calcium  carbonate 
sulphuretted    hydrogen:    CaS -fH,0       CO,  =  <  HJ3      As   the   sul- 

phuretted hydrogen  is  rather  dilute  and  variable  in  concentration,  tl 
led  through  a  fresh  quantity  of  the  waste,  by  which  it  i»  absorbed,  forming 
the  bisulphide:    CaS  —  H  _>  =  <  all  >..     When  kiln  gas  is  led  through  this 


MANUFACTURE  OF  CHARCOAL  AND  SULPHUR      71 

the  sulphuretted  hydrogen  is  again  given  off,  but  is  of  double  the  previous 
concentration  :  CaH 8Sa  +  H B0  +  CO ,  =  CaC03-f-  2H 2S.  This  gas  is  col- 
lected in  a  gas-holder,  and  can  be  fed  from  there  into  the  chambers  where  it 
is  converted  into  sulphuric  acid,  or  it  can  be  mixed  with  gas  from  the  pyrites 
burners,  whereby  sulphur  is  caused  to  deposit  in  accordance  with  the  equation  : 
2H2S  +  S02  =  2H20  +  3S.  The  sulphur  thus  obtained  is  of  considerable 
purity. 

Sulphur  is  also  obtained  in  the  purification  of  coal-gas  from  sulphuretted 
hydrogen  and  other  sulphur  compounds. 

Until  recently  the  market  was  entirely  controlled  by  an  English  associa-  Louisiana 
tion,  the  Anglo-Sicilian  Sulphur  Company,  formed  in  1895.  Sulphur  had  p 
been  found  in  Louisiana  in  1865,  during  some  boring  operations  for  petroleum, 
but  it  was  situated  underneath  500  feet  of  quicksand,  and  all  attempts  to 
work  it  commercially  failed  until  the  matter  was  taken  up  by  Hermann  Frasch 
in  1891,  and  even  then  years  of  work  were  required  and  a  large  amount  of 
capital  before  success  was  achieved.  The  sulphur  is  mixed  with  a  much 
smaller  proportion  of  limestone  than  in  Sicily,  the  ore  containing  about  70 
per  cent,  sulphur.  The  method  that  has  been  adopted  is  to  put  down  a  pipe 
of  10  inches  diameter  until  the  sulphur  deposit  is  reached,  then  the  hole  is 
continued  with  a  9-inch  drill  through  the  sulphur  deposit,  which  is  about 
200  feet  thick.  A  6-inch  pipe  is  passed  to  the  bottom,  and  a  3-inch  pipe 
through  this,  both  being  jjerforated  near  their  lower  ends.  Superheated 
water  is  passed  down  the  6-inch  pipe,  but  the  sulphur  passes  up  the  3-inch. 
At  first  it  was  raised  by  means  of  pumps,  but  now  air  is  forced  down  :  this 
mixes  with  the  sulphur  and  reduces  its  density,  and  it  is  raised  to  the  surface 
of  the  ground  by  the  pressure  of  the  water  used  for  melting. 

The  "  Union  Sulphur  Company  "  has  been  so  successful  that  it  has  acquired 
the  whole  of  the  trade  of  the  United  States  and  also  exports  considerable 
quantities.  The  production  amounts  to  several  hundred  thousand  tons  per 
annum. 

The  sulphur  as  it  comes  up  from  the  well  is  said  to  have  a  purity  of  99-93 
to  99-98  per  cent.  It  is  simply  run  into  great  bins,  which  hold  as  much  as 
150,000  tons  each.  When  it  has  cooled  the  sides  of  the  bins  are  removed,  the 
sulphur  is  broken  up,  and  is  then  readj^  for  shipment. 

The  Anglo-Sicilian  Sulphur  Company  finding  itself  unable  to  contend 
with  Frasch's  Company  finally  retired  from  the  business,  but  it  had  made 
enormous  profits  for  many  years.  The  Italian  Government  has  formed  a 
compulsory  trust  to  control  the  marketing  of  Sicilian  sulphur  and  ensure  a 
living  wage  to  the  Sicilian  workmen.  This  has  proved  very  successful  and 
the  workers  in  Sicily  are  now  better  off  than  they  have  been  for  many  years 
past. 

On  the  occasion  of  the  presentation  to  him  of  the  Perk  in  .Medal,  Frasch 


12  EXPLOSIVES 

gave  a  very  interesting  account  <>f  the  various  difficulties  he  had  to  contend 
with  in  working  out  his  invention,  and  this  is  published  in  tin-  /.  8       I       pa. 
//  ■/..   1912,  pp.    168   176.1 
&nins  Sicilian  sulphur  requires  \<>  be  refined  before  it  can  he  used,  and  thi>  i- 

done  by  distilling  it.     The  crude  or  *:  grough  *"  sulphuris  placed  in  an  iron  pot, 
which  i-  heate  1  from  below  by  a  furnace  until  the  sulphur  boils.     The  vapour 
passes  over  into   a   chamber  where   the   sulphur  is  deposited  en  the  walls  in 
the  form  of  small  crystals,  which  constitute  "  flowers  of  sulphur."     If  the  walls 
of  the  chamber  are  allowed  to  Lrct  hot  enough  to  melt  the  crystals  the  sulphur 
run-  down  and  is  tapped  otf  and  cast  into  -tick-  or  roll-.     The  -till  i-  often 
arranged  that  the  waste  heat  from  the  furnace  melt-  another  charge  of  crude 
Bulphur  ready  to  run  into  the  still  as  soon  a.-  the  first  charge  ha-  been  distil  • 
off.      The  refinery  at  Waltham  Abbey  is  provided  not    only  with    a    la:_ 
chamber  or  '"  dome  **  but  also  with  a  condenser  leading  to  a  receiver.     Only 
the  first  portion  of  vapour  is  admitted  to  the  dome,  then  the  vapours  are  tun 
into  the  condense]-.     Flowers  of  sulphur  are  not  tit   for  making  explosn 
because  they  contain  a  small  proportion  of  sulphuric  and  sulphurous  adds 
The  flowers  from  the  dome  are  therefore  redistilled. 
open:es.  1;  ,11  sulphur  consists  of  pale  yellow  brittle  crystals  l>elonLrinLr  t<»  the  rhombic 

system,  having  a  density  of  2  < '7  at  0  .    It  melt-  at  about  113  .  to  an  ami 
coloured  liquid,  hut  when  tin-  heating  i-  continued  above   120    it   gradually 
becomes  darker  and  more  viscous.     Between   160*   and 220    it  is  so  yu 
that   tin-  vessel  containing  it   can  be  inverted  without   losing  any.     If  this 
viscous  amorphous  mas-  be  cooled  rapidly  part  of  it  retains  the  amorphous 
condition   and   i-   insoluble   in   carbon    bisulphide,   which   dissolves   ordinary 
rhombic  sulphur  with  ease.     Flowers  of  sulphur  always  contain  a  proportion 
ot   this   insoluble  modification.     Sulphur  boils  at   444 
unctions  o!  due  reason  why  sulphur  i-  added  to  Hack  powder  is  that  its  temperature 

iiphur.  o|  j^jfj,,,,   L>(;|    ,'  jv  ](lW    all(|  consequently  it  makes  the  powder  burn  more 

readily.  Hut  another  reason  is  that  under  the  influence  of  pressure,  not  only 
in  the  press  hut  also  in  the  incorporating  mill,  it  flows  and  becomes  colloidal. 
cementing  together  the  particles  of  charcoal  and  the  minute  crystals  of  salt- 
petre. From  the  examination  of  microphotographs  Cronquist1  found  that 
brown  charcoal  ha-  a  similar  power  of  becoming  colloidal  under  pressure. 
This  i-  why  brown  gunpowders  burn  more  slowly  and  regularly  than  black, 
and  why  the  percentage  of  sulphur  in  them  can  he  reduced  or  abolished 
altogel  I:' 

Sulphur  oxidizes  slowly   in   the  air.  forming   sulphur  dioxide  and   a   little 
sulphuric  acid.      If  a    chlorate   he  present    chloric  acid  i-  liberated,   and  this 
elerates  the  oxidation,  and  there  i-  grave  danger  of  spontaneous  ignition 
occurring. 

1  >-<   also  s.s.   mil.  p.  236.  -    -  -..    1906,  p 


CHAPTER    VI 


MANUFACTURE  OF  GUNPOWDER 

Advantages  and  disadvantages  :  Composition  Grinding  the  ingredients: 
Weighing  and  mixing  :  Incorporating  or  milling  :  Automatic  drenchers  :  Remov- 
ing the  mill-cake  :  Breaking  down  :  Pressing  :  Granulating  or  corning  :  Dusting 
and  glazing  :  Stoving  or  drying  :  Finishing  and  blending  :  Cut  powders  :  Moulded 
powders  :  Blasting  powders  :  Sprengsalpeter  :  C'ahuecit  :  Petroklastit  :  Bobbinite  : 
Water-soluble  powder  :  Products  of  explosion 

The  invention  of  so  many  other  blasting  explosives  and  smokeless  powders 
has  greatly  restricted  the  consumption  of  black  powder,  but  it  has  been  able 
to  hold  its  own  in  certain  fields  in  consequence  of  its  advantages  .  its  low 
price,  the  ease  with  which  it  can  be  ignited,  its  insensitiveness  to  shock,  its 
stability  at  moderately  high  temperatures,  its  regular  rate  of  burning,  and 
the  non-corrosive  nature  of  the  residue  that  it  leaves  in  the  gu  1.  But  against 
these  must  be  placed  its  great  disadvantages  :  its  want  of  power  and  the 
great  quantity  of  smoke  that  it  evolves.  For  shot-guns  its  rate  of  explosion 
is  suitable,  only  the  recoil  and  smoke  are  disagreeable,  but  for  rifles  the  rate 
of  burning  cannot  be  controlled  sufficiently  :  for  driving  the  bullets  out  of 
shrapnel  shell  there  is  no  better  explosive,  and  it  is  still  used  for  armour-piercing 
shell,  because  the  high  explosives  used  for  other  sorts  of  shell  will  not  withstand 
the  great  shock  of  impact  wit'  out  exploding  prematurely  ;  for  filling  the  rings 
of  time  fuses  for  shell  no  satisfactory  substitute  has  yet  been  found. 

Guttmann.  in  his  book  on  the  Manufacture  of  Explosives,  published  in  Composition 
1895,  gave  the  following  as  the  compositions  of  the  principal  powders  made 
at  that  time  : 


Saltpetre 

Sulphur 

Charcoal 

(a)  Rifle  Powders  : 

Austria-Hungary      .... 

75 

10 

15 

Belgium.          ..... 

7. ">•."» 

12 

12-5 

China       ...... 

75 

10 

15 

France  ' . 

7.") 

in 

L5 

( lennany  ...... 

74 

10 

16 

1  Vermin  <t  Chesneau,  p.  322,  give  the  proportions  7.")  :  L2-5  :  L2-5. 

2  The  proportions  afterwards  used  in  Germany  for  rifle  powder  were  75  :  9  :  L5. 

73 


74 


EXPLOSIVES 


Saltpetre 

Sulphur 

(  hani.al 

(a)  Rifle  Pou-i 

Great   Britain . 

75 

10 

15 

Holland . 

7" 

14 

16 

Italy 

7.". 

in 

15 

i 

7.". 

12-5 

12-5 

•  ugal 

7. ".-7 

10-7 

13-6 

-..»     . 

7.". 

in 

15 

Spain 

75 

12-5 

12-5 

len  . 

75 

in 

15 

-       zerland 

" 

11 

14 

Turb 

75 

10 

15 

Unit* 

7."> 

10 

15 

(b)  Cannon  Powders  : 

Austria -Hungary- 

74 

10 

16 

France  J . 

75 

10 

15 

many         .... 

74 

10 

16 

■  at  Britain. 

75 

10 

15 

3    ltzt-rland      .... 

7.", 

10 

15 

(r)  S 

Austria -Hungary- 

76 

9*4 

14*6 

France    ..... 

78 

10 

12 

many         .... 

78 

10 

12 

•  at  Britain. 

" 

10 

15 

-     it  zerland      .... 

7> 

9 

13 

(d)  Blasting  Potodt 

Austria-Hungary 

60-2 

18-4 

21-4 

. 

7.' 

13 

15 

many         .... 

70 

14 

16 

•at  Britain. 

10 

15 

Italy        

70 

18 

12 

. 

lti-7 

16-7 

Blasting  powders,  however,  vary  in  composition  far  more  than  this  Table 
inch'    •  with  different  rates  ol  burning  being  used  for  rocks  of 

different  degrees  of  hardness.     Thus  the  French  Government  factories  make 

three  sorts  of  mining  powder  : 


Salt; 


Sulpb 


Charcoal 


Ordinary  Powder 
Slow  Powder 
:.g  Powder  . 


4<i 


20 
30 
13 


18 
3U 
15 


__'.  give  the  proporti"'.-  75     12*5     !-•"• 


MANUFACTURE   OF   GUNPOWDER  75 

The  powders  manufactured  in  Belgium  have  the  following  compositions  : 


Saltpetre 

Sulphur 

Charcoal 

Rifle  Powder           .... 

75 

12-5 

12-5 

Cannon  Powder      .... 

75 

12-5 

12-5 

Sporting  Powder    .... 

78 

10 

12 

Blasting  Powder    .... 

75 

12 

13 

Slow  Powder  or  Pulverin 

70 

13 

14  &  3%  wood  meal 

Slow  Powder  in  cartridges 

70 

13 

14  &  3%  dextrine 

Export  Powder      .... 

68 

18 

22 

In  France  "pulverin  "  is  also  prepared  for  the  manufacture  of  fireworks, 
etc.  According  to  Chalon  it  has  the  composition  75  :  12-5  :  12-5,1  but 
Vemiin  gives  the  proportions  as  62  :  20  :  18.2  h»4 

Before  they  are  mixed  together  the  three  ingredients  are  powdered.  As  Grinding  the 
they  are  not  explosive  when  separate,  they  can  be  ground  up  in  any  suitable  ingre  ients- 
mill.  In  this  respect,  however,  some  reserve  must  be  made  as  regards  the 
sulphur  :  this  has  a  great  tendency  to  become  electrified,  and  as  it  is  also 
very  inflammable  an  electric  spark  may  easily  set  it  alight  or  cause  the  explo- 
sion of  a  mixture  of  sulphur-dust  and  air.  Rapid-moving  machinery  is 
therefore  to  be  avoided  ;  the  parts  should  all  be  made  of  metal  and  "  earthed." 
According  to  Voigt  the  drum  for  pulverizing  sulphur  should  not  make  more 
than  ten  revolutions  per  minute.3  In  some  works  the  sulphur  is  mixed  with  a 
small  proportion  of  the  saltpetre  before  grinding  to  prevent  this  electrification, 
which  has  the  further  disadvantage  that  it  causes  the  sulphur  to  cake  together 
and  so  escape  proper  grinding.  At  Waltham  Abbey  the  sulphur  is  ground 
under  steel  edge-runners  similar  to  those  used  for  incorporating  the  powder. 

The  charcoal  is  generally  ground  in  a  machine  resembling  a  large  coffee 
mill  (see  Fig.  6),  but  in  some  factories  ball-mills  are  used,  the  charcoal  being 
placed  in  a  drum  with  bronze  balls.  The  drum  is  then  rotated  until  the 
constant  falling  of  the  balls  on  to  the  charcoal  has  reduced  it  to  a  sufficiently 
fine  state  of  division. 

Sulphur  and  saltpetre  may  also  be  ground  in  the  Excelsior  mill,  but  if 
the  saltpetre  is  already  in  fine  crystals  it  need  not  be  ground,  but  only  sifted. 
In  France  the  saltpetre  is  mixed  with  6  per  cent,  of  charcoal  and  pulverized 
in  an  iron  drum  with  bronze  balls.  The  charcoal  makes  the  saltpetre  easier 
to  grind,  and  this  small  proportion  does  not  make  it  explosive.  The  remainder 
of  the  charcoal  is  mixed  with  the  sulphur  and  pulverized  in  a  similar  drum. 
After  grinding  these  binary  mixtures  are  passed  through  a  sieve  with  holes 


1  Explosifs  Modernes,  pp.  228,  203.  2   Vennin  et  Chesncau,  p. 

8  Herstellung  der  Sprengstoffe,  vol.  i.f  p.   52. 


322. 


v. 


EXPLOSIVES 


5  mm.  in  diameter  to  separate  foreign  matters.  The  two  binary  mixtures 
are  then  mixed  together  by  hand  before  being  milled. ] 

The  three  ingredients  are  carefully  weighed  out,  preferably  each  in  separate 
scales.  An  extra  amount  of  saltpetre  Is  often  taken  to  allow  for  the  moisture  in 
it.  the    actual   proportions    weighed    out    being    sometii         "  :  10  0 

instead  of  75*0  :  15*0  :  L0-0.     But  the  charcoal  usually  contain-  quite  as  h  _ 

ntage  of  moisture  as  the 
saltpetre.  It  is  not  surprising 
therefore  that  analysis  sometimes 
show-  a  percentage  of  charcoal 
which    i-    below   the   theoretical. 

The  ingredients  are  tin n  _ 
a    preliminary   mixing.     In    I 
many  this  is  done  in    a  rotating 
drum     with    lignum    vita?    halls. 
The  drum   is  made  of    wood   and 
may  be  lined    with  leather  ;  iron 
must  be  avoided   iii    ts  construc- 
tion ;    the  axle   must  be  coi 
with  leather.     At  Waltham  Abbey 
the  mixing  is  done  in  a  cylindrical 
drum    of     copper    or    Lrun- 
about     18    inch.  -    long    and  2  feet 

'.•  inches  in   diameter.     Through 

the  centre  passes  an  axle  carrying 

eight    low-    ,,f    fork-shaped   arms. 

called       "'  tl\  i  The       drum 

rotates    in  one  direction   making 

4<i  revolutions  per    n  inute.     The 

axle   moves  in  the  other  direction 

and    make-     120    revolutions    p<  r 

minute.      The     ingredients     are 

mixed  for  live  minute-,  and  then  sifted  through  a  fine-mesh  sieve  of  copp 

brass  wire.     The  sifting  at  this  stage  is  very  important,  a-  any  hard  particles 

left  in  the  charge  are  likely  to  cause  an   explosion  in  the  incorporating  mill. 

For  this  reason  the  sifting  is  sometimes  done  by  hand.     The"  green"  c 

i-  now  placed  in  a  waterproof  bag  ready  to  he  taken  to  the  incorporating  mill. 

(>n  the  Continent  stamp- mi  lis  are  -till  used  to  a  small  extent  for  incorporat- 
ing a-  well  as  mixing  gunpowder.  I  n  <  Sermany  the  stamp-heads  may  be  made 
of  copper,  zinc,  bronze  or  other  suitable  alloy.-'  The  charge  iv  placed  in  a 
spherical  hole  in  a  block  <»f  wood,  with  a  |>i»  i  ially  hard  wood  in-. 

1    \'t>iitiit   it  ( 'In  sin  n  a.   ]i.    327.  nfaUrtrhuitungt  ten,    1912,   i> 


Fig.  6. 


Excelsior  Mill,  made  by  Maschineabau 

A.-G.   '  ■■  '!.•<■! 'ii-<  irinu 


MANUFACTURE   OF  GUNPOWDER 


77 


at  the  bottom  for  the  stamp  to  play  upon.     The  stamping  is  carried  on  for 
about  fourteen  hours.     If  continued  longer  the  density  of  the  powder  diminishes 

and  the  ballistics  deteriorate. 

In  France  the  use  of  stamp-mills  was  definitely  abandoned  in  1SS4.1   the 
powders  there  being  incorporated  in  drums  and  mills.     The  cheaper  sorts  of 
powder    are    incorporated 
entirely  in  drums  contain- 
ing    wooden     balls.      In 
England  also  stamp-mills 
are    not    used,     and     the 
standard    method    is    to 
grind  the  ingredients   to- 
gether    in     incorporating 
mills.        Formerly      these 
consisted    of    two    heavy 
stone  edge-runners  work- 
ing on  a    stone  bedplate. 
Now  it  is    more  usual  to 
have  iron    runners  work- 
ing on  an  iron  bed-plate  ; 
of  course  iron    must   not 
work  upon  stone,  or  vice 
versa,  on  account  of    the 
danger    of    genera  ting- 
sparks.    In  the  most  usual 
type   of  mill  the  runners 
are  G  or  7  feet  in  diameter 
and  about  15  inches  wide, 
and  weigh    about   4  tons 
each.     They  rotate  on  the 
opposite  ends   of   a   hori- 
zontal    shaft,      which     is 
carried    by    a    cross-head, 
which   again    is   attached 

to  a  vertical  shaft  making  about  eight  revolutions  a  minute.  Usually  the  two 
edge-runners  are  mounted  at  different  distances  from  the  central  shaft  so 
that  one  works  the  outer  part  of  the  charge  and  the  other  the  inner,  but  their 
paths  overlap.  There  are  two  ploughs  of  wood  covered  with  leather,  which 
are  fixed  to  the  shaft  and  travel  round  with  it.  These  continually  push 
the  charge  away  from  the  centre  and  the  curb  respectively,  and  bring  it 
under  the  edge-runners  again.     The  mills  make  1\  or  8  revolutions  per  minute. 

1  P.  ,t  >'..   \<»1.   iii.,   e.    is. 


Fig.  7.     Gruson  Gunpowder  Mill. 


EXPLOSIVES 

In  the  Grusou  mill  (Fig.  7)  the  iron  runners  do  not  rest  on  the  bed  but  are 
•nded  a  short  distance  above  it,  so  that  there  is  no  danger  of  a  very  thin 
layer  of  powder  being  subjected  to  great  friction.     The  bearings  are  bo 
pended  that  either  runner  can  travel  upwards  independently  of  the  other 

when  an  extra  thick  portion  of  charge  comes  underneath  it.  The  runners 
weigh  about  5|  tons  each  and  rotate  equidistantly  round  the  main  vertical 
Bhaft.  The  ploughs  are  made  of  phosphor  bronze,  and  each  runner  is  also 
provided  with  a  Bcraper  to  prevent  the  charge  being  thrown  off  the  bed.  The 
drive  is  by  mean-  of  a  la:  _  lied  gear-wheel,  which  may  be  arranged  either 

above  the  machine  or  below  it. 

In  Germany  iron  runners  are  not  allowed  to  work  on  an  iron  bed-plate 
unless  they  are  suspended,  as  in  the  Gruson  mill.  If  they  actually  rest  upon 
the  bed.  it  must  be  made  of  wood  fastened  down  with  brass  screws. 

By  the  action  of  the  runners  the  ingredients  are  crushed  and  ground  to- 
gether very  intimately  without  subjecting  the  mixture  to  any  violent  action. 

Usually  about  six  incorporating  mills  are  arranged  in  a  row  and  driven  from 
a  common  shaft  actuated  by  a  single  water-wheel  or  steam-engine.  Each  mill 
■arated  from  the  next  by  a  strong  masonry  wall.  Explosions  in  these  mills 
are  fairly  frequent  in  spite  of  even-  precaution,  but  as  a  rule  no  very  serious 
damage  is  done.  In  1907  there  were  nine  such  explosions  in  England,  but 
only  one  man  was  injured  ;  in  1908  there  were  five  explosions  and  two  men 
were  injured  ;  in  1909  there  were  seven  explosions  and  no  men  were  injured. 
The  reason  why  there  are  so  few  men  killed  or  injured  in  these  accidents  is 
that  as  a  rule  there  is  no  one  in  the  mill  house  :  after  the  charge  has  been 
Btarted  the  man  in  attendance  goes  on  to  see  to  other  mills  and  only  comes 
occasionally  to  see  that  all  is  right  and  to  add  a  little  water  to  the  charge  if 
necessary.  In  France  there  is  less  than  one  explosion  in  100,000  milling 
operations.1  In  Germany  no  workman  is  allowed  to  remain  in  the  building 
whilst  the  mill  is  working  at  full  speed. 

A  charge  consis-  i  80  lbs.,  the  time  of  incorporation  varies  with  the 

iption  of  the  powder  :  the  longer  the  incorporation  the  faster  the  powder 
burns.  Cannon  powders  were  usually  milled  for  three  or  four  hours,  rifle 
a  eight,  and  sporting  powders  as  much  or  more.  The  charge  when 
placed  in  the  mill  contains  2  to  3  per  cent,  of  moisture.  It  must  be  kept  moist 
the  whole  time  ;  for  this  purpose  the  mill-man  adds  Mater  from  time  to  time, 
preferably  condensed  water  from  a  steam  trap.  Formerly  urine  was  frequently 
used  instead  of  water.  For  fine  grain  powders  l{  to  3  per  cent,  of  moisture 
should  be  present  in  the  finished  mill-cake,  for  larger  sizes  3  to  6  per  cent. 

In  France  mills  similar  to  the  Gruson  mill  are  used,  but  the  charge  is  only 
2o  ktr.  or  2.")  kg.  in  the  case  of  mining  powder.  It  contains  8  per  cent,  moisture 
when  introduced  and  2  to  4  per  cent,  at  the  finish.     The  mill  makes  10  revo- 

1_Vennin  ct  Ch-csneau,  p.  333. 


MANUFACTURE   OF   GUNPOWDER 


79 


lutions  per  minute  and  requires  7  horse-power.     The  following  table  gives 
the  times  of  milling  and  the  densities  of  the  mill  cake  : 


Time 

Density 

Military  rifle  powder,  F3 
Sporting  powder,  ordinary 

,,                  ,,          strong 
Dust   reworked          .... 
Mining  powder         .... 

.     2  - 

.      H 

5 

i 

•          i 

M 

hours     1-740 
1-725 
1-80 

1-57 

The  density  is  of  importance  because  in  France  the  powder  is  not  pressed. 
The  density  can  be  increased  by  milling  slowly,  half  a  turn  per  minute,  with 
the  outer  plough  removed.1 

In  Germany  the  charge  is  generally  about  75  kg.  and  the  mill  makes  about 
nine  revolutions  per  minute.     The  time  of  milling  is  : 


Military  powder 
Sporting        „ 
Mining  ,, 


2J-3  hours 
H 


0= 


Fig.   8.     Drenching  Arrangements  for  Powder  Mills. 


Before  the  charge  is  removed  the  mill  is  run  slowly  for  a  time  to  increase  the 
density,  but  the  powder  undergoes  a  pressing  operation  also,  except  in  the  case 
of  mining  powder.2 

In  order  to  prevent  the  explosion  in  one  mill  being  communicated  to  the  Automatic 
other  mills  of  the  group,  each  one  is  provided  in  England  with  an  automatic  drenchers- 
drenching  arrangement  (see  Fig.  8).  This  consists  of  a  lifting  board  /,  provided 
with  a  counterpoise  weight.  There  is  also  a  tank  t  full  of  water,  supported 
on  a  hinge  and  a  leg  at  one  end  that  rests  on  a  projection  from  the  lifting 
board.  When  the  latter  is  lifted,  the  leg  is  released,  the  tank  tips  forward 
and  the  water  is  poured  over  the  charge  in  the  mill.     The  axle  a  is  common 


1  Vermin  et  Chesneau,  p.   332. 

2  Voigt,  Herstellung  der  Sprengstoffe, 


pp. 


56. 


8o 


EXPLOSIVES 


Removing  the 
mill-cake. 


Breaking 
down. 


Pressing. 


t<>  all  the  lifting  boards  of  the  group  of  mills,  bo  thai  if  there  be  an  explosion 
in  one  of  the  mills  the  corresponding  board  /  is  raised,  taking  with  it  all  the 
other  similar  boards,  and  all  the  charges  in  the  group  are  drenched  and  bo 
rendered  unexplosive.  In  order  t<>  make  the  mechanism  sufficiently  sensitive 
;t  is  important  thai  the  boards  be  not  too  small  and  not  too  near  the  roof,  and 
that  they  be  directly  over  the  mills.     The  second  point  is  essential,  because  if 

the  hoard  he  very  near    the  roof    a    reflected 

wave  of  pressure  reaches  it  almost  imme- 
diately after  the  direct  wave  and  before  the 
mechanism   has   had  time  to  act. 

The  mill-cake  often  becomes  caked  on 
lo  the  bed  very  firmly.  Many  accidents 
having  been  caused  by  removing  tlh>  with 
metal  tools.  H.M.  [nspector  of  Explosives 
issued  a  letter  on  December  27,  1883,  pro- 
posing the  adoption  of  the  following  special 
rule  in  all  black  powder  works  : 

"  Whenever  it  may  become  necessary  in 
mills  or  other  buildings  to  remove  any 
powder  incrustations  (whether  from  the 
machinery  or  elsewhere),  which  cannot  be 
easily  brushed  off,  Buch  removal  is  to  he 
effected  without  the  use  of  any  metal  tool 
whatever  ;  the  hard  powder  i>  to  be  removed 
by  means  of  water,  supplemented,  if  need 
be,  when  the  whole  incrustation  has  been 
thoroughly  saturated.  by  a  suitable  wooden 
instrument  gently  applied." 

Tin-  mill-cake  is  next  reduced  to  a  tough 
powder  by  hand  or  by  passing  it  through 
gun-metal  rolls  in  a  machine  somewhat 
resembling  the  granulating  machine,  but 
simpler. 

Then  the  mixture  is  subjected  to  high  pressure  in  a  |  it--.     This  converts 
it  into  a  hard  mass,  the  constituents  of  which  have  no  tendency  to  separate 

again    from    one    another,    and    also    increases    the    density    of    the   powder. 

Formerly  the  powder  was  compressed  in  a  very  strong  box,  hut  this  is  no 
longer  done  on  account  of  the  dangerous  friction  against  the  -ides. 

For  moulded   powders  and   blasting  cartridges  special  presses  are  used, 
which  will  be  described  later.     Granulated  powders  are  pressed  in  presses  of 

the  type  shown  in  Fig.  (.'.  The  mill  cake  i-  •  milt  up  on  a  small  trolley  :  first 
a  plate  of  copper,  bronze,  or  ehomte  i>  put  down,  and  a  temporary  frame  put 


Fig.  9.     t  lunpowder  Press. 


MANUFACTURE   OF  GUNPOWDER  81 

round  it.  then  a  layer  of  the  mill-cake  about  f-inch  thick  is  carefully  spread, 
then  another  plate  and  another  layer  of  powder,  until  about  10  cwt.  of  mill-cake 
has  been  built  up  with  about  twenty  plates.  The  temporary  frames  are  then 
removed  and  the  trolley  is  wheeled  on  to  the  press,  and  the  pressure  is  gradually 
applied.  The  amount  of  compression  required  varies  with  the  amount  of 
moisture  in  the  mill-cake  and  the  density  to  be  attained  in  the  finished  powder. 
For  a  mixture  containing  about  .'>  per  cent,  of  moisture  it  is  necessary  to  apply 
a  pressure  of  about  400  lb.  per  square  inch  of  plate  surface  for  1|  to  2  hours 
to  obtain  a  density  of  IT.  The  amount  of  compression  is  measured  by  the 
motion  of  the  press  rather  than  by  the  hydraulic  pressure  ;  this  motion  may  be 
24  or  30  inches  according  to  the  dimensions  of  the  press,  etc.  The  pressure 
is  usually  released  and  reapplied  several  times  to  obtain  a  satisfactory  result. 

Ebonite  plates  are  sometimes  preferred  to  metal  because  they  keep  their 
shape  better  and  yet  give  sufficiently  to  transmit  the  pressure  evenly.  If  the 
cake  be  very  dry  the  ebonite  may  become  electrified,  however,  and  so  produce 
very  dangerous  sparks.  In  Germany  the  use  of  ebonite  plates  is  forbidden, 
and  cloths  are  laid  between  the  plates  and  the  powder.  The  four  columns  of 
the  press  should  be  made  of  mild  steel  with  an  ample  margin  of  strength  even 
if  the  whole  pressure  is  borne  by  only  two  of  them.  They  may  with  advantage 
be  covered  with  leather.  It  was  recommended  by  H.M.  Inspector  of  Explo- 
sives x  that  the  press  should  not  be  worked  directly  off  the  hydraulic  pump, 
but  from  an  accumulator,  and  that  the  drive  of  the  pump  should  not  be  positive. 
but  by  friction. 

The  explosion  of  a  press-house  is  more  destructive  than  that  of  any  other 
building  in  a  black  powder  works,  as  might  be  expected,  considering  that 
there  is  about  half  a  ton  of  powder  in  one  mass  strongly  compressed.  The 
house  should  therefore  be  specially  well  isolated  from  other  buildings  by  mounds, 
etc.  In  some  works  the  workmen  are  not  allowed  to  be  in  the  press-house 
whilst  the  pressure  is  on  the  powder  ;  the  pressure  can  be  applied  and  controlled 
from  another  compartment,  where  there  is  also  an  indicator  showing  the  position 
of  the  platform  of  the  pro-. 

When  sufficiently  pressed  the  pressure  is  released  and  the  trolley  is  wheeled 
away,  and  the  press-cake  removed  from  it  by  hand  or  with  wooden  tools.  The 
outer  portion  of  each  slab  is  rejected  as  it  is  not  sufficiently  compressed  :  it  is 
added  to  a   later  pressing. 

Blasting  powder  is  sometimes  compressed  between  rollers. 

The  broken-up  press-cake  is  put  in  barrels  and  taken  to  the  granulating  Granulating 
or  corning  house.     Here  there  is  a  machine  having  three  or  four  pairs  of  gun- 
metal  rolls,  through  which  the  press-cake  is  passed,  and  a  number  of  automatic 
sieves,  which  sort  out  the  grains  of  the  required  si/.e  i  >"   Fig.   10).     The  top 
pair  of   rollers   usually   has  pyramidal   teeth  :     from    this  the   material   passes 

1  Special   Report    No.    138. 

VOL.   I.  6 


32 


EXPLOSIVES 


over  a  sieve  to  the  next  pair  of  rolls,  which  has  smaller  teeth.  The  lowest 
paii  are  plain.  The  pieces  that  are  not  tine  enough  are  passed  through  the 
machine  again  ;    the  dust  and  tine  powder  are  milled  for  a  short  time  and 


In.     Corning  Machine,  made  by  Mascninenhau  A.-G.  Golzern-Grimma 

m.     The  bearings  of  one  <■!   both  rolls  "f  each  pair  ait-  provided 

with  »piiiiLr-  or  weights  t<>  keep  them  in  position,  and  are  not  rigidly  fixed. 

Consequently  if  an  extra  hard  piece  of  cake  passes  through  tin-  rolls  it  i-  not 

subjected  to  great  violence  :   the  rolls  give  way  and  the  piece  passes  through. 

This  type  "f  granulating  machine  was  invented  in  IS19  by  <  'olonel  <  bngreve, 


MANUFACTURE   OF   GUNPOWDER 


83 


and  is  the  one  in  most  general  use.  Various  other  types  have  been  tried,  but 
none  produces  such  a  good  angular  grain. 

In  France  the  granulation  is  carried  out  in  a  horizontal  drum  covered  with 
metal  sheet  perforated  with  fine  holes  of  a  size  suited  to  the  sort  of  powder  that 
is  to  be  produced.  The  broken  down  mill-cake  is  placed  inside  this  drum  to- 
gether with  pieces  of  hard  wood,  which  are  caused  by  longitudinal  strips  to  fall 
continually  on  to  the  powder  and  break  it  up.  A  charge  of  20  kg.  is  granulated 
in  ten  to  twelve  minutes  and  yields  35  to  55  per  cent,  of  grains  of  the  size  required. 

Powders  made  with  dog-wood  charcoal  produce  a  lot  of  dust  in  the  corning  Dusting 


Fig.    11.*    Corning  Machine  with  Dust-Remover 

process,  and  it  is  best  to  remove  this  by  passing  the  powder  through  a  dusting 
reel.  This  is  simply  a  cylindrical  reel  set  at  an  angle  of  about  4°  to  the  hori- 
zontal and  covered  with  fine  woven  wire  of  copper  or  brass.  It  is  open  at 
both  ends  and  rotates  on  its  axis,  making  about  forty  revolutions  per  minute. 
The  powder  is  simply  passed  through  this  and  caught  again  in  a  barrel. 

The  glazing  operation  is  carried  out  in  wooden  drums,  which  rotate  on  Glazing, 
their  axis  about  thirty  times  a  minute.     Cannon  powders  receive  an  addition 
of  a  small  proportion  of  graphite  and  are  glazed  for  two  or  three  hours.     Rifle 
and  sporting  powders,  and  others  thai  are  required  to  burn  quickly,  do  uo1 
receive  any  graphite,  but  are  glazed  longer. 

The  -love  may  be  heated  either  by  forcing  hoi  air  through  it.  or  by  arranging  Stoymg  or 


^4 


EXPLOSIVES 


hot  water  or  .-team  pipes  in  it.  The  easiest  and  most  economical  method  is 
to  dry  with  steam,  and  as  Mark  powder  is  qo!  very  sensitive  and  is  not  liable 
■  II-  decomposition,  this  method  is  usually  adopted.  Only  low- 
pressure  Bteam  should  be  used,  the  exhaust  being  open  to  the  air.  The  powder 
i-  placed  on  canvas  trays  supported  on  wooden  racks,  [nlete  and  outlets  are 
provided  for  the  air.  and  the  temperature  is  kept  at  about  4n  c.  (i<>4  F.). 
The  time  required  t<>  dry  the  powder  varies  from  one  to  four  hours  according 
to  the  size  <>f  grain. 

To  remove  the  last  tract's  of  dust  and  give  the  powder  a  good  "colour" 
it  i-  now  treated  for  some  two  hours  in  tin-  tini-hinu:  reel,  which  i-  covered  with 
fine  canvas,  and  finally  thoroughly  blended  into  Large  uniform  batches.  The 
last  operation  i-  performed  at  Waltham  Abbey  by  pouring  it  into  a  hopper, 
which  is  provided  with  four  delivery  shutes,  so  that  the  contents  of  tin-  hopper 
are  divided  into  four  ecpial  portions.  By  repeating  this  operation  in  a 
systematic  manner  the  desired  object   is  attained  very  effectually. 

Powder  for  cannon  of  large  size,  6  to  12-inch  bore,  was  made  by  cutting 
the  press-cake  into  cubes.  The  >lahs  from  the  pre--  were  passed  under  a  roll 
armed  with  longitudinal  knives,  whereby  the  cake  was  cut  into  strips,  and  these 
were  then  passed  under  another  similar  roll  in  the  other  direction  and  so  cut 
into  cubes.  The  glazing,  stoving,  finishing  and  blending  were  very  much  as 
for  granulated  powder,  except  that  the  stoving  had  to  he  continued  for  about 
thirty  hours  at  .">:.  I  .  These  cut  powders  arc  but  little  made  now.  as  they 
have  been  displaced  by  smokeless  powd 

The  folio  wing  Table  gives  particulars  of  some  of  the  powders  made  formerly 
at  Waltham  Abbey  1 : 


of 
grains 

CharooaT 

Q. 

Finishril  Powder 

Pow- 
der 

Time 

M      - 

ine 
r:m„     tun-      , 

1  in. 

Wood 

burn- 
ing 

t             "1 
nrs.         ... 
inul- 

eake 

nrs. 

hrs. 

Temp. 

Dei 

stun 

RFG 

12  20 

Dogw. 'I'd 

4   bXB. 

4       1- 

1 

100    1". 

1-58    1-62 

0-9  -1-2 

RFC 

12  20 

8      .. 

8      2-5         10 

2 

100 

1-72    1-75 

0-9  -1-2 

RL& 

Alder  and 

willow 

:;     2-5          l ; 

2 

110 

1-65 

1*0   1-3 

RLG« 

- 

4      .. 

3       4 

115 

1-65 

1*0  1-3 

P 

|*   Clll><- 

4      .. 

3                       4 

130 

l-:.-. 

1-0-1-3 

Moulded  powders  also  arc  but  little  used  for  the  same  reason,  but  much  the 
same  process  is  used  for  making  moulded  cartridges  of  mining  powder,  and  also 
1  7'  Service  .    1907  ed.,  pp.   123,   1-4. 


MANUFACTURE   OF   GUNPOWDER 


85 


pellets  for  time  and  percussion  fuses  and  for  other  ammunition.     The  general 
form  of  all  these  articles  is  practically  the  same  :  a  hexagonal  or  round  cylinder 


Fig.  12.     Hydraulic  Automatic  Press  for  Moulded  Powders  and  Blast  Lag  ( 'art  ridges 
(Maschinenbau  A.-G.  Golzern-Grimma) 

with  a  central  perforation.  The  powder  is  pressed,  granulated,  dusted  and 
blended  as  already  described,  and  then  taken  to  the  moulding  house.  Two 
different  types  of  press  are  used,  worked  by  hydraulic  and  mechanical  pressure 


86 


EXPLOSIVES 


respectively  |  s«  Figs.  1-  and  13).  The  general  principle  is,  however,  the  same. 
The  granular  powder  i>  put  into  a  hopper  and  flows  from  there  into  a  measure 
that  automatically  measures  "IT  the  right  quantity,  which  then  passes  into  the 

die.  The  dies  an-  arranged  in  rows  in  a  plate,  bo  that  whilst  one  row  is  being 
filled  another  i>  being  pressed.     The  pressure  i>  usually  applied  simultaneously 

from  above  and  below  by  two 
different  plungers.  The  cen- 
tral hole  is  formed  by  means 
of  a  pin  which  passes  through 
the  lower  plunger  and  into 
the  other.  Hydraulic pressi  - 
are  safer,  but  mechanical 
ones  more  rapid  in  their 
action.  For  blasting  car- 
tridges, machines  are  also 
made  with  rotating  tables 
containing  a  number  of  dies  : 
each  operation,  rilling,  j>ress- 
ing,  removing,  is  performed 
at  a  different  position  of  the 
table.  Such  machines  are 
quite  automatic  and  require 
very  little  attention. 

Both  black  and  brown 
powders  have  been  moulded 
into  prisms  which  are  usually 
25  mm.  high  and  40  mm. 
wide,  measured  across  the 
comers     of     the     hexagons. 


Fi'..ji:'..     Mechanical  Press  for  Moulded 

etc.  (F.  Krupp  A.-6.   Grusonwerk) 


Powdei  -.! 


The  following 

Tabic  gives  the  details 

of  the  E 

iglish  and  ( ierman 

powders  : 

<  iountry 

Ml.' 

(  harcoal 
Black   . 

Propirtions 

Density 

England 

Prism1  Black       . 

76      :   10  :    L6 

1-76 

.. 

Prism1    Brown 

I  '•■  ■  »wn . 

79          ::  :  18 

1-80 

.. 

E.X.E. 

.. 

77-4    :      5    :    17-6 

1-80 

,, 

S.B.C. 

79      :     3  :    18 

1-85 

m\- 

P.P.C./68  . 

Black   . 

74       :    10   :    16 

1-66 

P.P.C.   75  . 

71        :    10    :    16 

1-76 

.. 

P.P.I      82 

Brown . 

7  s              3        19 

1-80 

,, 

P.] 

.. 

BO           0  :  20 

1-88 

France  ' 

J*.B.. 

.. 

7^           3  :  19 

1-85    1-87 

Ohesneau,  pp.  322,  341. 


MANUFACTURE    OF   GUNPOWDER 


87 


P.P.C./68  has  seven  holes,  all  the  others.  English  and  German,  only  one.  The 
value  of  the  brown  straw  eharcoaUis  that  under  the  high  pressures  it  flows 
and  holds  the  mixture  together,  making  it  into  an  impervious  mass,  which 
can  only  burn  at  the  surface,  whereas  black  powders  have  slight  pores  through 


BLACK     BLASTING    POWDER 
GRADED 


BLACK    BLASTING    POWDER 
MIXED      GRAINS 


FFFF 


«MW«F2S 


FFF 


Fig.   14.     American    Black  Blasting  Powders  (Munroe  and  Hall) 

which  the  flame  can  penetrate.     This  may  be  seen  by  examining  the  powders 
under  the  microscope.1 

The  usual  composition  of  Mack  blasting  powders  has  already  been  stated  Blasting 
(p.  74).     The  violence  of  the  powder  can  be  varied  by  altering  the  composition, 
the  density  or  the  size  of  the  grains  :   the  powder  is  made  slower  by  diminish- 
ing the  percentage  of  saltpetre,   compressing  to  a   higher  density  or  making 
1  See  Cronquist,  S.S.,   1906,  p.  53. 


powders. 


&8 


EXPLOSIVES 


77-1 

74 

9-4  In  14-3 

10 

22 

16 

- ••! .     Iii  France  the  mining  j„  -     lanufactured  in  the  8l 

mills  are  incorporated,   not   and  .  but   in  copper  drum-  with 

wooden  and  bronze  ball-,  and  the  granulation  is  ah  1  in  drama  with 

the  aid  of  a  spray  of  water. 

In  America  enormous  quantities  of  blasting  powder  are  used  containing 
urn  nitrate  (Chili  saltpetre)  instead  of  the  potassiam  Bait.  This  burns 
more  slowly  than  ordinary  gunpowder,  but  i-  more  powerful,  as  it  evolves 
a  greater  volume  of  gas  and  more  heat,  but  its  principal  advantage  is  its  low 
f.  .i  it  i-  used  for  many  purposes  where  in  Europe  hand  labour  would 
be  employed.  According  to  Chalon,1  the  compositioD  varies  between  the 
following  limits  : 

Sodium  nitrate        .... 
Sulphur  ..... 

Charcoal  ..... 

The  usual  proportion-  in  this  "  black  blasting  powder  "  are  given  by  Munroe 
and  Hal'.  -     -  73  :  11  .  16.     The  incorporation  is  not    so   thorough   as   in   the 
-     of  ordinary  black  powder,  and  the  charcoal  is  generally  obtained  from 
ser-grained  woods.     As  the  -odium  nitrate  i>  hyg     -     pic,  care  must  be 
taken  doI  •  the  powder  to  damp  air  more  than  can  be  helped.     The 

following  are  thi  s  of  American  black  blasting  powdert 

Diameters  of  round  holes  in  screens  in  7'jth  int. 

Through  which  grains  On  which  grains 

pass 

40 

24 
18 
12 

u  : 

3 

The  following  blasting  explosives  resembling  black  powder  in  composition 
are  made  in  Germany,  and  are  allow-  sent  as  goods  in  unlimited  quanti- 

ridered   safer  to  handle  than  ordinary  black  pon 
Sprengsaipeter        "  Sprengsalpel  •la-ting   saltpetn       a        mixture   of   Bodium   nit 

sulphur  and  brown  coal  in  about  the    proportions    7.")  :  10  :  15,   and    i- 
largely  used  in  tl     Si     out  salt-mines  where  the  soft  and  brittle  nature  of  the 
-alt-,  such  as  carnallite,  require  an  explosive  that  is  milder  than  ordinary 
blasting  -  the  advai  bage  of  _    sheap  and  not  giving 

-  inous  fume-.     H  materials,  such  as  sylvinite  and  rock-salt, 


OCX 

c 

V     . 

FT 

PTF 

FFFF 

Ird   »-d..    1911, 

u  1911,  p. 


16. 


MANUFACTURE    OF   C IX  POWDER  SO 

are  blasted  with  a  combined  charge  of  nitro-glycerine  explosive  and  Spreng- 
salpeter. 

"  Cahuecit  "   was  invented    by   R.   Caluic  some  forty  years  ago  and  was  Cahuecit. 
manufactured  at  one  time  at  Dartford  under  the  name  of  Safety  Blasting 
Powder  or  Carboazotine.     It  had  the  composition  : 

Saltpetre        .......      0-4 

Sulphur 12 

Lampblack    .......        7 

Bark  or  wood-pulp         .  .  .  .  .17 

to  which  was  added  1  to  5  per  cent,  of  sulphate  of  iron.  After  mixing  the 
ingredients  roughly  in  a  drum  they  were  introduced  together  with  a 
considerable  bulk  of  water  into  a  steam-jacketed  pan  where  the  mixture  was 
heated  with  constant  stirring  until  almost  dry.  The  mixture  was  im- 
perfect in  consequence  of  the  tendency  of  the  soluble  salts  to  crystallize  out.1 
It  is  still  manufactured  in  Germany,  and  has  been  found  good  for  blasting 
basalt.2  The  official  German  definition  is  :  a  compressed  mixture  of  not  more 
than  70  per  cent,  saltpetre,  8  per  cent,  lampblack,  about  12  per  cent,  flowers 
of  sulphur,  at  least  10  per  cent,  cellulose,  and  a  small  quantity  of  iron 
sulphate. 

"  Petroklastit  "  (Haloklastit)  has  approximately  the  following  composition  :  Petrokiastii 

Sodium  nitrate       .  .  .  .  .  .09 

Potassium  nitrate  .....        5 

Sulphur 10 

Coal  tar  pitch        .  .  .  .  .  .15 

Potassium  bichromate    .....        1 

Its  strength  and  sensitiveness  as  compared  with  black  blasting  powder  3  are  : 

Trauzl  test  Falling  weight 

Petroklastit     .  .  .  .157  . .  100 

Black  powder  ...      108  .  .  05 

Its  official  definition  is  :  a  compressed  mixture  of  sodium  nitrate,  sulphur, 
coal-tar  pitch,  saltpetre,  and  not  more  than  1  per  cent,  potassium  bichromate. 
also  with  an  addition  of  not  more  than  10  per  cent,  charcoal.  It  has  been 
used  in  stone  quarries  and  potash   mines. 

In  English  coal-mines  the  most  largely  used  explosive  lias  been  Bobbinite, 
which  is  a  black  powder  mixture  with  an  addition  of  the  sulphates  of  copper 
and  ammonium,  or  of  starch  and  paraffin-wax.  It  is  t lie*  only  explosive  of 
this  class  that  was  able  to  pass  the  Woolwich  test  for  "  Permitted  Explo- 
sives "  ;    it  does  not  pass  the  Continental  and  Rotherhain  tests.     In  1906  a 

1  Guttmann,  Manufacture,  vol.  i.,  p.  '2!'.\  ;  see  also  Cundill  and  Thomson,  p.  142, 

2  S.S.,    1908,  p.   97.  ;'  Zschokke,   pp.   42,   57. 


Bobbinite. 


!MI 


EXPLOSIVES 


Departmental  Committee  was  held  at  the  Home  Office  to  inquire  whether 
this  explosive  should  be  removed  from  the  list.  This  has  not  been  done,  but 
by  the  Explosives  in  Coal-Mines  Order  of  September  1.  1913.  ite  use  has  been 
restricted  to  mines  that  are  not  gassy  or  dusty.  In  these  it-  use  i-  permitted 
for  a  period  of  five  years  from  January  1.  11)14.  The  following  is  its  composi- 
tion according  to  the  official  definitions,  and  an  analysis  made  by  Hall  and 
Howell  :  » 


<  Official  definitions 

Hall  and 

Fust                       -     <>nd 

Howell 

Nitrate  of  potassium 

Charcoal         ..... 

Sulphur          ..... 

Sulphate  of  ammonium] 

Sulphate  of  copper 

Rice  or  Maize  starch 

Paranin   wax            .... 

Mi 'ist  ure         ..... 

- 

62-0-65-0 

1 7-0-19-.-, 
1-5-2-5 

13-0-17-0 
0-0-  2-5 

63-0-66-0 

18-5-20*5 

1-5-  2-5 

7-0-  9-0 
2-5  -3-5 

nit  -  3-0 

31 
2-63 

8-'73 
3-35 
9*46 

owder. 


In  1914  more  than  a  million  lbs.  of  Bobbinite  were  used  in  British  mines 
and  quarries. 
Vater-soluble  Kaschig  proposes  to  make  a  cheap  blasting  powder  consisting  of  G.">  per 
cent,  sodium  nitrate  and  35  per  cent,  sodium  cresol-sulphonate.  These  are 
dissolved  in  water  and  the  solution  is  evaporated  very  rapidly  on  a  rotating 
drum  heated  by  high-pressure  steam.  It  is  claimed  thai  the  expensive  and 
dangerous  operation  ot  incorporation  is  thus  done  away  with.  It  i-  necessary 
to  select  a  combustible  constituent  like  the  cresol-sulphonate,  that  has  a  high 
solubility  of  the  same  order  as  the  nitrate,  otherwise  there  would  be  a  tendency 
for  the  substances  to  separate  during  the  evaporation.  Safety  explosives 
containing  ammonium  nitrate  instead  of  the  Bodium  sail  have  been  registered 
under  the  name  of  "  Raschit."2 

The  products  formed  on  the  explosion  of  gunpowder  were  investigated 
by  Bunsen  and  Schischkoff.3  Linck.4  and  Karolyi,6  but  the  most  complete 
series  of  experiments  was  carried  out  by  Noble  and  Abel.6     Debus7  Bhowed 

1  U.S.   Bureau  of  Mines,   Hull.    15,    1912,  p.    179. 

2  See  Ang.   1912,  p.   1194;    Ger.  Pat.  App.  R.  54,360  of  3/2/12  ;    N.N.,   1912,  p.  292. 

3  Pogg.  Annalen,  102,  1857,  p.  321.        4  Annalen  der  Chemie,  109,  1858.  p.  53. 

5  Pogg.  Annalen,  April,   1863;    Phil.  Mag.,  Ser.  4.   No.  26,    1863,  p.  266. 

6  Phil.    Trans..    1875,    49. 

7  Proc.  Roy.  Soc.,  30,   1880,  p.  198;    Phil.   Trans.,    1882,  p.  523. 


roducts  of 
zplosion. 


MANUFACTURE   OF   GUNPOWDER 


91 


that  they  had  made  an  error  in  giving  potassium  hyposulphite  as  a  primary 
product  of  the  explosion.  Noble  and  Abel  *  accordingly  corrected  their  results. 
The  mean  percentages  from  R.L.G.  Powder  were  : 


Gases 

.      42-98% 

Solids 

.      55-91 

Water 

1-11 

Gases,  per  cent,  by  volume 

Solids,  per  cent,  by  weighl 

Carbon  dioxide 

49-3 

Potassium  carbonate 

Carbon  monoxide     . 

12-5 

Potassium  sulphate 

Hydrogen 

2-2 

Potassium  sulphide. 

Methane 

0-4 

Potassium  sulphocyanide. 

Nitrogen 

32-9 

Potassium  nitrate    . 

Sulphuretted  Hydrogen    . 

2-6 

Sulphur             .... 

61-0 
15-1 

14-5 
0-2 
0-3 

8-7 

From  1  g.  of  the  powder  271-3  c.c.  of  gas  were  produced,  measured  at  760  mm. 
and  0°  C,  and  the  quantity  of  heat  liberated  was  700-7  calories. 

The  products  obtained  from  mining  powder  have  been  given  by  J.  Harger,2 
and  the  analysis  of  the  gases  from  American  blasting  powder  has  been  published 
by  C.  M.  Young.3  Hall  and  Howell  4  have  investigated  the  products  from 
Bobbinite. 

1  Phil.   Trans.,   1880,  p.   203. 

2  J.  Soc.  Chem.  Ind.,   1912,  p.  415. 

3  Bull.  Am.  Min.  Eng.,   1910,  pp.  637-662;    Aug.,   1911,  p.   1886. 

4  U.S.  Bureau  of  Mines  Bull.   15,   1912,  p.   179. 


PART  III 

ACIDS 


CHAPTER  VII 
SULPHURIC  ACID 

Manufacture  :  Purification  :  Concentration  :  Melting-points  :  Specific  gravities  : 
Calculations  :  Supplies  in  war-time 

The  manufacture  of  sulphuric  acid  is  treated  fully  in  special  works  such  as  Manufacture. 
Lunge's  Sulphuric  Acid  and  Alkali.     Here   only  the  general  principles   can 
be  dealt  with  and   those   special  features  which   are   of  importance   to   the 
manufacturer  of  explosives. 

Until  the  end  of  the  last  century,  or  the  beginning  of  this,  practically  all 
the  sulphuric  acid  was  made  by  the  "  chamber  process."  Now  very  large 
quantities  are  produced  by  the  "  contact  process."  In  both  processes  the 
first  stage  is  to  burn  sulphur,  or  a  sulphur  ore  such  as  zinc-blende  or  pyrites, 
in  an  excess  of  air,  thus  producing  a  gaseous  mixture  consisting  mostly  of 
oxygen,  nitrogen,  and  sulphur-dioxide.  It  is  necessary  now  to  make  the  sul- 
phur-dioxide combine  with  a  further  quantity  of  oxygen.  In  the  chamber 
process  this  is  done  by  mixing  a  small  proportion  of  oxides  of  nitrogen  with 
the  gases  and  water  in  the  form  of  spray  or  steam.  Various  intermediate 
products  are  formed,  but  the  final  product  is  "  chamber  acid,"  containing  about 
70  per  cent,  sulphuric  acid  and  30  per  cent,  water,  or  "  Glover  tower  acid," 
containing  about  80  per  cent.  acid. 

In  the  contact  process  the  sulphur-dioxide  is  made  to  combine  with  oxygen 
to  form  the  trioxide,  SO3,  by  passing  the  gases  over  a  heated  contact  substance, 
such  as  platinum  or  iron  oxide.  The  burner  gases  are  purified  by  washing 
with  water  and  sulphuric  acid,  but  afterwards  no  steam  or  spray  of  water  is 
introduced,  and  consequently  it  is  not  necessary  afterwards  to  concentrate 
the  acid  to  bring  it  up  to  a  high  strength,  as  is  the  case  with  the  chamber 
process.  On  the  contrary  the  sulphur-trioxide  has  to  be  absorbed  in  weak 
sulphuric  acid  so  as  to  obtain  an  acid  of  convenient  strength.  Very  great 
difficulties  were  experienced  at  first  because  after  a  short  time  it  was  found 
that  the  spongy  platinum  used  as  the  contact  material  ceased  to  be  active.  It 
was  discovered,  however,  that  this  was  due  to  the  presence  in  the  gases  of  traces 
of  impurity,  such  as  arsenic,  which  "poisoned  "  the  platinum.  When  these 
are  entirely  removed  the  contact  material  retains  its  activity  for  a  long  time. 
The  principal  motive  of  the  inventors  in  working  out  the  contact  process  was 

95 


96  EXPLOSIVES 

to  produce  at  a  reasonable  cost  a  fuming  acid  for  use  in  the  manufacture  of 
artificial  indigo,  but  Large  quantities  of  Btrong  acid  arc  also  required  in  the 
explosives  industry,  and  Borne  explosives  works  have  in  fad  erected  contact 

plants  of  their  own. 

In  the  burners  pyrites  is  generally  burnt,  bul  sometimes  blende.  The 
burnt  pyrites  or  blende  is  afterwards  scut  to  smelting  works,  where  the  metal 
is  extracted.  Sulphur  (brimstone)  is  used  only  in  localities  where  there  are 
no  Bmelting  works  available. 

Purification.  For  the  manufacture  of  explosives  a   high  degree  of  purity  is  generally 

required  of  the  sulphuric  acid,  especially  freedom  from  arsenic.  Acid  made 
by  the  contact  process  always  has  sufficient  purity,  as  arsenic  and  other  foreign 
substances  arc  necessarily  removed  in  the  course  of  manufacture.  Sulphuric 
acid  made  from  pyrites  by  the  chamber  process  generally  contains  a  consider- 
able amount  of  arsenic  and  other  impurities.  These  can  be  removed  by 
treating  the  acid  with  sulphuretted  hydrogen  and  allowing  it  to  settle  before 
concentrating  it. 

Concentration.  Acid  of  To  per  cent,  strength  can  often  he  concent  rated  up  to  SO  per  cent. 

by  passing  it  down  a  Glovei  tower.  Where  this  is  not  available  the  concen- 
tration is  generally  carried  out  in  lead  pans  heated  either  by  a  fire  underneath 
or  by  steam  coils  laid  in  the  bottom  of  the  pan.  Above  this  strength  lead 
pans  cannot  be  used  as  they  are  attacked  too  much  by  the  hot  acid.  For 
the  production  of  pure  water-white  concentrated  sulphuric  acid  the  further 
concentration  may  be  carried  out  in  glass  or  platinum  stills  heated  from  below  . 
The  greater  part  of  the  water  i-  thus  distilled  off  together  with  a  little  acid. 
The  glass  stills,  however,  are  liable  to  break  and  the  consumption  of  fuel  is 
considerable.  Platinum  is  very  expensive  and  has  risen  in  price  considerably 
of  late  years.  The  platinum  is  Bometimes  coated  with  gold  to  diminish  the 
loss.  In  neither  glass  nor  platinum  can  sulphuric  acid  of  the  highest  strength 
We  produced  :  to  obtain  this  a  further  concent  ration  in  cast-iron  pans  is  necessary. 
Those  works  that  have  a  contact  sulphuric  acid  plant  can  use  their  recovered 
acid  to  absorb  t  he  sulphur-trioxide,  and  so  bring  it  up  to  any  required  strength. 
In  factories  where  the  acid  is  purchased  the  same  object  can  be  accomplished 
by  mixing  the  weak  recovered  acid  with  fuming  acid  i  X.O.Y.)  '  containing  i'n 
or  60  per  cent,  anhydride.  But  in  some  processes  of  manufacture  as.  for 
instance,  the  displacement  process  for  gun-cotton,  such  large  quantities  of 
weak  acid  are  produced  thai  rcconcenl  ra  t  ion  is  necessary.  Such  reconcent  ra- 
tion is  nearly  always  carried  out  in  the  explosives  works  themselves,  as  it 
does  not  pay  to  transport  such  a  material  backwards  and  forwards  by  road 
or  rail. 

1  The  commercial  term  for  sulphuric  acid  "t"  92  to  96  per  cent,  strength  (s.g.   1*83 
1-84)  is  ( '.( >.  V.  (concentrated  "il  of  vitriol),  thai  of  the  Fuming  acid  containing  anhydride 
is  X.o.V.  (Nordhausen  <>ii  of  vitriol)  or  oleum. 


SULPHURIC   ACID  97 

The  concentration  is  carried  out  either  in  a  "  cascade  "  plant  or  by  direct  asca  ep 
contact  with  hot  gases.  In  the  cascade  plant  the  acid  is  made  to  flow  in  turn 
through  a  large  number  of  beakers  or  basins,  each  one  of  which  is  at  a  slightly 
lower  level  than  the  last.  These  are  all  heated  from  below  by  means  of  a 
suitable  furnace.  Formerly  the  vessels  were  made  of  glass  or  porcelain,  but 
much  trouble  was  caused  by  the  continual  breakages.  Now  basins  of  fused 
silica  ware  or  special  iron  are  used  and  breakages  are  comparatively  rare. 

A  type  of  plant  used  very  extensively  in  the  explosives  industry  is  that  Kessler's 
of  Kessler,  the  principle  of  which  is  to  bring  a  current  of  hot  gas  from  a  gas  Plant- 
producer  in  contact  with  the  acid  in  a  plant  constructed  of  volvic  stone,  which 
is  only  very  slightly  attacked  by  the  hot  concentrated  acid.  Fig.  15  shows 
an  early  form  of  the  plant,  which  has  since  been  modified  in  some  details.  The 
hot  gas  from  the  producer  enters  by  the  tube  O  into  the  "  saturex  "  S,  where 
it  passes  down  the  channels  q,  and  is  caused  by  baffles  to  rush  over  the  surface 
of  the  acid  into  the  channels  q1.  From  here  it  passes  up  through  the  "  pla- 
teaux "  A,  B,  C,  D,  where  the  inverted  cups  cause  it  to  bubble  through  the 
acid  which  passes  down  from  one  plateau  to  the  other  by  means  of  the  over- 
How  pipes  n.  The  acid  thus  receives  a  preliminary  concentration,  and  the 
gas  is  partially  cooled  down  before  it  goes  through  the  dome  Z  and  the  pipe  P 
to  the  condenser.  The  weak  acid  is  introduced  on  the  top  plateau,  and  the 
concentrated  acid  flows  out  of  the  saturex  through  the  pipe  m  into  a  lead  tank, 
where  it  is  cooled  by  means  of  a  coil  through  which  water  flows.  The  arrange- 
ment of  the  baffles  in  the  saturex  has  now  been  altered  ;  they  run  transversely 
to  the  direction  of  flow  of  the  gas  and  acid,  and  the  hot  gas  passes  under  each 
of  them  in  turn. 

The  gas  passing  away  through  P  carries  with  it  a  considerable  amount  of 
sulphuric  acid,  mostly  in  the  form  of  very  fine  mist,  which  is  very  difficult 
to  remove  and  is  very  injurious  to  the  surroundings.  The  gas  is  therefore 
passed  through  a  condenser  consisting  of  a  large  lead  tank  packed  with  care- 
fully graded  coke.  Formerly  the  gas  was  drawn  off  by  means  of  a  steam  injec- 
tor in  the  pipe  P,  but  this  was  very  extravagant  in  steam  and  caused  the 
condensed  acid  to  be  very  dilute.  Now  a  fan  is  used  instead.  Water  is 
sprayed  into  P  to  assist  the  condensation  of  the  acid.  The  general  arrange- 
ment of  the  plant  is  shown  in  Fig.  16.  Careful  regulation  of  temperatures 
and  draughts  is  necessary  to  ensure  the  best  results. 

In  deciding  what  strength  of  oleum  it  is  best  to  use  one  of  the  properties  Melting- 
that  must  be  carefully  considered  is  that  of  the  melting-points  of  the  acids.    In  pomts- 
Fig.  17  (pp.  104-5)  are  given  the  values  as  determined  by  Knietsch  and  published 
by  him  in  the  important  paper  on  the  contact  process,  which  he  read  before  the 
German  Chemical  Society  in  October  1901. 1    It  will  be  seen  that  there  are 

1  Ber.,   1901,  4093;    Chcm.  Ind.,   1902,  p.  6. 
VOL.  I.  7 


■ 


■  i . ...  ■ 1 .1    *i     ,1     t     ,  *i ^      i 


i 

Sectional  Elevation 


t — — 

.r 

t 

-  \        , 

1 

f     

7 

■■(■■'■    ■>■■■■■■'' 

.* 

~ T 

1 

J 

i;     ! 

.    " 

f 

; 

- 

-*~  r 

s 

> 

1                        q 
1 

f 

■      1 

d^ 

1.' 

,  ■■;  1 

■""■'   r 



1 

' "f    ' 

7 

!    I, 

— -H 

' 

Sectional  Plan 
Fig.   15.     Keealer  ( loncentratoi 

98 


SULPHURIC   ACID 


99 


Elevation 


Plan 


SS.H 


Fig.    16.     Arrangement    of   Kessler'a    Plant    for   the 
("lie.  nt  rat  ion   of   Sulphuric    Acid 


100  EXPLOSIVES 

maxima  at  the  point>  corresponding  to  iH2S04.  H.O).  (Hj304),  (H«S04.  S03) 
and  (S03).  and  minima  at  intermediate  point-.    A  strength  that  is  much  used 

ie  containing  Is*  to  2o  per  cent,  anhydride  :  it  has  the  advantage  that  it  is 
liquid  at  all  ordinary  temperatures.  With  an  increase  of  strength  the  melting- 
point  rise-  rapidly  until  with  4.".  per  cent,  anhydride  it  reaches  36:,  a  tempera- 
ture at  which  it  i>  very  inconvenient  to  deal  with  an  acid  that  gives  off  dense 
fumes  even  at  the  ordinary  temperature  and  boils  below  90°.  From  here 
the  melting-point  falls  again  until  with  a  strength  of  60  to  65  per  cent,  anhy- 
dride an  add  is  obtained  which  is  liquid  in  summer  and  can  be  easily  melted 
at  any  time  of  the  year.  The  choice  of  acid  to  be  used  therefore  rests  between 
1  O.V.  and  N  I  'V  containing  18  to  20  per  cent,  and  60  to  65  per  cent,  anhy- 
dride.    The  decision  must  depend  on  the  price  at  which  the  acids  can  be 

:ned  and  the  facilities  for  reconcentrating  or  using  the  weak  acids  produced 
in  manufacture.     Where  such  facilities  are  deficient  it  is  better  to  use  the 

iger  oleum.     Very  little  waste  acid  will  then  be  produced.     Otherwise 
si  works  prefer  to  use  the  2o  per  cent,  oleum.     C.O.V.  is  now  little  used 
in  explosives  works  for  revivifying  waste  acids. 

One  of  the  disadvantages  of  the  20  per  cent,  oleum  is  that  it  attacks  iron 
much  more  strongly  than  either  C.O.V.  or  the  60  per  cent,  oleum.1  On  the 
other  hand,  the  vapour  tension  of  the  weaker  oleum  i>  considerably  smaller 
than  that  of  the  stronger.  Whereas  C.O.V.  containing  '-,s •">  per  cent.  H.v|  > 
boils  at  .'ilT  .  and  100  per  cent,  acid  at  about  27o  .  2<»  per  cent,  oleum  boils 
at  about    14o     and  60  per  cent,  at  60     C. 

I  the  specific  gravities  of  mixtures  of  sulphuric  acid  and  water 
have  been  published  by  various  investigators.  There  are  slight  differences 
between  the  best  of  them,  due  principally  to  the  difficulty  of  determining  the 
strength  of  the  acid  with  a  very  high  degree  of  accuracy,  and  perhaps  partly 
to  the  presence  of  traces  of  impurity  in  the  material.  The  Tables  of  Lunge 
and  his  co-workers  Xaef  and  I>ler  are  much  used,  but  upon  the  whole  the 
figures  of  Pickering  seem  to  be  the  best.  Many  of  the  Tables  are  not  directly 
comparable  because  the  specific  gravities  have  been  taken  at  different  tempera- 
tures or  are  referred  to  water  at  different  temperatures  ;    in  some  cases  the 

;tie>  are  corrected  for  air  displacement  and  in  others  not.  For  general 
work  it  i>  best  to  weigh  both  the  acid  and  water  at  the  ordinary  temperature 
and  not  '  rect  for  air  displacement,  for  the  introduction  of  small  eorrec- 

i  is  not  <»nly  troublesome  but  is  liable  to  lead  to  error.  Pickering's  figun  5 
were  therefore  calculated  by  me  to  this  basis,1  and  are  given  in  the  following 
Table  : 

1  8et  Knietsoh.  lor.  ■.,,..   Tnd.,   L903. 


SULPHURIC  ACID 

Specific  Gravities  of  Sulphuric  Acid  at  15°/15°C.  in  Air. 


101 


Specific 
gravity 

0 

1 

2 

3 

4 

5 

6 

7 

8 

9 

1-00 

0-00 

0-14 

0-28 

0-43 

0-57 

0-71 

0-86 

1-01 

1-15 

1-30 

1-01 

1-45 

1-60 

1-75 

1-89 

2-04 

2-19 

2-34 

2-49 

2-64 

2-79 

1-02 

2-93 

3-08 

3-23 

3-38 

3-53 

3-67 

3-82 

3-97 

4-12 

4-26 

1-03 

4-41 

4-56 

4-70 

4-85 

5-00 

5-14 

5-29 

5-44 

5-58 

5-73 

1-04 

5-88 

6-03 

6-17 

6-32 

6-46 

6-60 

6-75 

6-89 

7-04 

7-18 

1-05 

7-32 

7-47 

7-61 

7-76 

7-90 

8-04 

8-19 

8-33 

8-47 

8-62 

1-06 

8-76 

8-90 

9-04 

9-18 

9-33 

9-47 

9-61 

9-75 

9-89 

10-03 

1-07 

10-17 

10-31 

10-45 

10-59 

10-73 

10-87 

11-00 

11-14 

11-28 

11-42 

1-08 

11-56 

11-69 

11-83 

11-97 

12-11 

12-24 

12-38 

12-52 

12-66 

12-79 

1-09 

12-93 

13-07 

13-20 

13-34 

13-48 

13-01 

13-75 

13-89 

14-02 

14-16 

MO 

14-29 

14-43 

14-56 

14-70 

14-83 

14-97 

15-10 

15-24 

15-37 

15-51 

Ml 

15-64 

15-78 

15-91 

16-05 

16-18 

16-31 

10-45 

16-58 

16-71 

16-84 

1-12 

16-98 

17-11 

17-24 

17-37 

17-51 

17-64 

17-77 

17-90 

18-03 

18-16 

1-13 

18-30 

18-43 

18-56 

18-69 

18-82 

18-95 

19-08 

19-22 

19-34 

19-47 

1-14 

19-60 

19-73 

19-86 

19-99 

20-12 

20-25 

20-38 

20-51 

20-64 

20-77 

M5 

20-90 

21-03 

21-16 

21-28 

21-41 

21-54 

21-07 

21-80 

21-93 

22-05 

1-16 

22-18 

22-31 

22-44 

22-56 

22-69 

22-82 

22-94 

23-07 

23-20 

23-32 

M7 

23-45 

23-57 

23-71 

23-83 

23-96 

24-08 

24-21 

24-34 

24-46 

24-59 

1-18 

24-71 

24-84 

24-97 

25-09 

25-22 

25-34 

25-47 

25-59 

25-72 

25-84 

1-19 

25-97 

26-09 

26-22 

26-34 

26-47 

26-59 

26-71 

26-84 

26-96 

27-09 

1-20 

27-21 

27-33 

27-46 

27-58 

27-71 

27-83 

27-95 

28-08 

28-20 

28-32 

1-21 

28-45 

28-57 

28-69 

28-82 

28-94 

29-06 

29-18 

29-31 

29-43 

29-55 

1-22 

29-68 

29-80 

29-92 

30-04 

30-17 

30-29 

30-41 

30-53 

30-65 

30-78 

1-23 

30-90 

31-02 

31-14 

31-26 

31-38 

31-50 

31-62 

31-75 

31-87 

31-99 

1-24 

32-11 

32-23 

32-35 

32-47 

32-59 

32-71 

32-83 

32-95 

33-07 

33-19 

1-25 

33-31 

33-43 

33-55 

33-67 

33-79 

33-91 

34-02 

34-14 

34-26 

34-38 

1-26 

34-50 

34-62 

34-74 

34-86 

34-98 

35-09 

35-21 

35-33 

35-45 

35-57 

1-27 

35-68 

35-80 

35-92 

36-04 

36-15 

36-27 

36-39 

36-51 

36-62 

36-70 

1-28 

36-86 

36-97 

37-09 

37-21 

37-32 

37-44 

37-56 

37-68 

37-79 

37-91 

1-29 

38-03 

38-14 

38-26 

38-37 

38-49 

38-60 

38-72 

38-83 

38-95 

39-06 

1-30 

39-18 

39-29 

39-41 

39-52 

39-64 

39-75 

39-86 

39-98 

40-09 

40-20 

1-31 

40-32 

40-43 

40-54 

40-66 

40-77 

40-88 

40-99 

41-11 

41-22 

41-33 

1-32 

41-45 

41-56 

41-67 

41-79 

41-90 

42-01 

42-12 

42-23 

42-35 

42-46 

1-33 

42-57 

42-68 

72-79 

42-90 

43-01 

43-12 

43-23 

43-35 

43-46 

43-57 

1-34 

43-68 

43-79 

43-90 

44-01 

4412 

44-23 

44-34 

44-45 

44-56 

44-67 

1-35 

44-77 

44-88 

44-99 

45-10 

45-21 

45-32 

45-43 

45-53 

45-64 

45-75 

1-36 

45-86 

45-97 

46-07 

46-18 

46-29 

46-39 

46-50 

46-61 

46-71 

46-82 

1-37 

46-92 

47-03 

47-14 

47-24 

47-35 

47-45 

47-:>0 

47-07 

47-77 

47-88 

1-38 

47-!IS 

48-09 

48-19 

48-30 

48-40 

48-50 

48-61 

48-71 

48-82 

48-92 

1-39 

49-02 

49-13 

49-23 

49-34 

49-44 

4«.K-.4 

49-65 

49-75 

49-86 

49-96 

1-40 

50-06 

50-10 

50-26 

50-37 

50-47 

50-57 

50-67 

50-77 

50-88 

50-98 

1-41 

51-08 

51-18 

51-28 

51-38 

51-48 

51-58 

51-68 

51-78 

51-8!) 

51-99 

1-42 

52-09 

52-19 

52-29 

52-39 

52-49 

52-59 

52-69 

52-79 

52-89 

:.l'-!is 

1-4:5 

53-08 

53-18 

53-28 

53-38 

53-48 

5  3 -.18 

53-68 

53-78 

53-88 

53-97 

1-44 

.->4-07 

54-17 

54-27 

.->4-:w 

54-46 

54-56 

54-65 

54-75 

54-85 

54-94 

102 


EXPLOSIVES 


Specii  i i    ( 

Jrayities  of  Sulphuric  Aoid 

AT     l.V 

L6    C    r.    An: 

continued 

Specific 
gravity 

0 

1 

1' 

:{ 

4 

5 

6 

7 

8 

'.i 

1*46 

55-04 

56-14 

55-24 

55-33 

55-43 

55-53 

55-62 

55-72 

1 
65-82 

55-91 

1-46 

56-01 

56-]  1 

56-20 

66-30 

56-39 

56-49 

56-59 

56-68 

56-78 

56-87 

1-47 

66-97 

57-06 

57-16 

57-25 

57-35 

..7-44 

57-54 

57-63 

57  -7  3 

57-82 

1-48 

57-92 

58-01 

.-.s-|ii 

5S-2M 

58-29 

58-38 

58-48 

58-57 

58-66 

58-76 

1-49 

58-85 

59-94 

59-03 

59-12 

59-22 

59-31 

50-41 

59-50 

59-59 

59-68 

1-50 

59-78 

59-87 

59-96 

60-05 

60-14 

60-23 

60-33 

60-42 

60-51 

60-60 

1-51 

00-69 

60-78 

60-87 

60-96 

61-05 

61-14 

61-24 

61-33 

61-42 

61-51 

1-52 

61-60 

61-69 

61-78 

61-87 

61-96 

62-05 

62-14 

62-23 

62-32 

02-41 

1-53 

62-50 

62-59 

62-68 

02-77 

62-86 

62-95 

63-04 

63-13 

63-22 

63-31 

1-64 

63-40 

63-49 

63-58 

63-67 

63-76 

63-85 

63-94 

64-03 

64-12 

64-20 

1-55 

64-29 

64-38 

04-47 

64-55 

64-64 

64-73 

64-82 

04-01 

65-00 

65-08 

1-56 

65-17 

65-26 

65-35 

65-44 

65-52 

65-61 

65-70 

65-79 

65-88 

65-96 

1-67 

66-05 

66-14 

66-23 

66-31 

66-40 

66-49 

66-57 

66-66 

66-75 

66-83 

1-58 

66-92 

67-01 

07-10 

67-18 

67-27 

67-36 

67-44 

67-53 

67-62 

67-70 

1-59 

67-79 

67-88 

67-97 

68-05 

68-14 

68-23 

68-31 

68-40 

68-49 

68-57 

1-60 

68-66 

68-74 

68-83 

68-92 

69-00 

69-09 

69-17 

69-26 

69-35 

69-43 

1-61 

69-62 

69-60 

69-69 

69-78 

69-86 

69-95 

70-03 

70-12 

70-20 

70-29 

1-62 

70-38 

70-46 

70-55 

70-63 

70-72 

70-80 

70-89 

70-97 

71-06 

7114 

1-63 

7i-i':; 

71-31 

71-40 

71-48 

71-57 

71-65 

71-74 

71-82 

71-91 

71-99 

1-64 

72-07 

72-16 

72-25 

72-33 

72-42 

72-60 

72-59 

72-07 

72-76 

72-84 

1-65 

72-93 

73-01 

73-10 

73-18 

73-27 

73-35 

73-43 

73-52 

73-60 

73-69 

1-66 

73-77 

73-86 

73-94 

74-02 

74-11 

74-19 

74-27 

74-30 

74-44 

74-53 

1-07 

74-61 

74-69 

74-78 

74-86 

74-95 

75-03 

75-12 

75-20 

75-29 

75-37 

1-68 

76-46 

75-54 

75-63 

75-71 

75-80 

75-88 

75-97 

76-05 

76-14 

70-21* 

1-69 

76-31 

76-39 

76-48 

76-56 

76-65 

76-74 

76-82 

76-91 

76-99 

77-08 

L-70 

77-17 

77-2.-. 

77-34 

77-42 

77-51 

77-60 

77-68 

77-77 

77-85 

77-94 

1-71 

7s-<>:; 

78-11 

78-20 

78-28 

78-37 

78-46 

78-54 

78-63 

78-72 

78-80 

1-72 

78-89 

78-97 

79-06 

79-15 

79-23 

79-32 

79-41 

79-49 

79-58 

79-67 

L-73 

79-75 

79-84 

79-93 

80-02 

80-11 

80-20 

80-29 

80-38 

si  1-4  7 

80-56 

1-74 

80-65 

80-74 

80-83 

80-92 

81-01 

81-10 

81-19 

81-28 

81-37 

SI -40 

1-75 

81-55 

81-64 

81-73 

81-82 

81-92 

82-01 

82-11 

82-21 

82-31 

82-41 

1-76 

82-51 

82-61 

82-71 

82-80 

82-90 

83-00 

83- 10 

83-20 

83-29 

83-39 

1-77 

S.-J-49 

83-59 

83-69 

83-78 

83-88 

83-98 

84-08 

84-18 

84-29 

84-39 

1-78 

84-50 

84-60 

84-71 

84-81 

84-92 

85-03 

85-14 

85-25 

85-36 

85-47 

1-7!) 

86-60 

85-72 

85-84 

85-96 

86-08 

86-20 

86-32 

86-45 

so.;,s 

80-71 

L-80 

86-84 

86-97 

87-10 

87-23 

87-36 

87-50 

87-64 

87-78 

87-92 

88-06 

1-81 

SVL'I, 

ss-:;i 

88-49 

88-64 

88-79 

88-95 

S'.l-|  1 

89-27 

89-4  I 

89-61 

1-82 

89-79 

89-97 

90-15 

90-33 

90-51 

90-70 

90-90 

91-10 

91-30 

91-52 

1-83 

91-74 

91-98 

92-22 

92-46 

92-7] 

92-98 

93-26 

93-56 

93-87 

94-20 

1-84 

lit -.-.7 

94-96 

95-40 

96-02 

96-93 

1-84 

ll'.t-SS 

99-61 

99-29 

98-84 

98-08 

1-8442 

97- 

r,(i 

1-8394 

100- 

00 

SULPHURIC  ACID 


103 


For  concentrated  acid  the  determination  of  the  specific  gravity  is  not  of 
much  value  as  an  indication  of  its  strength,  because  the  density  reaches  a 
maximum  at  about  97-5  pel  cent. 

The  following  Table  gives  the  corrections  to  be  applied  to  the  specific 
gravities  if  the  temperature  varies  from  I00.1 

gp.  (Jr.  Correction  for  1° 

Up  to   1-170  •     0-0006 


1-170 
1-450 
1-580 
1-750 


1-450 
1-580 
1-750 
1-820 


0-0007 
0-0008 
0-0009 
0-0010 


For  the  effect  of  impurities  on  the  specific  gravity  of  sulphuric  acid  see 
Marshall,  J.  Soc.  Chcm.  Ind.,  1902,  p.  1508.  Fig.  18  (p.  106)  gives  the  specific 
gravities  of  a  number  of  trade  samples  of  C.O.V.,  some  of  which  had  become 
contaminated  with  traces  of  nitric  acid,  also  some  acids  that  had  been  used 
and  reconcentrated  several  times  in  a  Kessler  plant.  The  curves  correspond- 
ing to  the  Tables  of  Pickering  and  Lunge  are  also  given  for  comparison. 

Knietsch  has  determined  the  specific  gravities  of  fuming  acids  (loc.  cit.). 
His  figures  are  to  be  found  in  the  following  Table  : 


Free  S03 

Total  S03 

Corresponding 

Sp.  gr.  15715° 

Sp.  gr. 

45° 

per  cent. 

H2S04 

in  air 

10 

83-46 

102-2 

1-888 

1-858 

20 

85-30 

104-5 

1-920 

1-887 

30 

87-14 

106-7 

1-957 

1-920 

40 

88-97      • 

109-0 

1-979 

1-945 

50 

90-81 

111-2 

2-009 

1-964 

(max.) 

60 

92-65 

113-5 

2-020  (max.) 

1-959 

70 

94-48 

115-7 

2-018 

1-942 

80 

96-32 

118-0 

2-008 

1-890 

90 

98-16 

120-2 

1-990 

1-864 

100 

100-00 

122-5 

1-984 

1-814 

The  strength  of  the  fuming  acid  is  generally  expressed  as  per  cent,  free  Calculations 
S03,  but  sometimes  as  total  S03.  When  determining  the  strength  by  analysis 
it  is  most  convenient  to  express  it  first  as  per  cent.  H2S04,  and  there  are  other 
advantages  in  expressing  it  thus.  A  figure  is,  of  course,  obtained  which  is 
greater  than  100,  but  it  gives  at  once  the  quantity  of  sulphuric  acid  that  will 
be  formed  if  100  parts  of  it  be  added  to  a  mixture,  and  if  100  be  deducted  from 
it,  the  remainder  is  the  amount  of  water  that  will  disappear  from  the  mixture 
to  form  this  sulphuric  acid.  This  remainder  multiplied  by  S03/H20  (  = 
1  Lunge  and  Hurter,  Alkali-Maker's  Pocket-book. 


SULPHURIC  ACID 


FUSION  CURVE 
MELTING  POINT  CURVE 
CRYSTALLISATION  CURVE 

MELTING  POINT  CURVE 
ETC.  OP  OLEUM  NOT 
YET  POLYMERISED 


3C 

~ 

♦ 

» 

* 

„-**« 

z 

•  i\ 

ft 

'~                   _ 

*„ 

'  / '                  ^v 

/                                       \.                                                                                                                                                              J 

1                                                      \                                                                                                                                           '  H 

,       .  , 

— ^ -\ V~ 

/                                                                                                                  \              '  \                                                          I'J          I 

/    '                                                                             \         ,   >                                       i  r       *     "" 

/   '                                                                     v            \                                               '  /' 

/    '                                               '                                     \ 

H^SO,,  75  j 


v    co.v.  w[.v;h2S 

Fig.  17.     Melting-Points  of  Sulphuric 


104 


S03free 


-A3°C 


Acid  and  Oleum  (Knietsch) 


105 


106 


EXPLOSIVES 


&> 

i 

■- 

— ' 

-t&l— 

...     |._ 

* 

> 

» 

tti 

*  O-r 

•     ' 

A^ 

p 

>o*+ 

j 

m 

(••- 

4 

- 

J 

N 

• 

,  i| 

•  '.  < 

f*«S 

„ 

91 

* 
• 

t 

4*& 

_A  1 

New                 * 
Reconcentratid* 

MinReS.             oil 

HNOj            (-ojv 

JSL^ 

^ 
^ 

u* 

'«$ 

1SS^V»^^  X  -O 

14*0 

"tMv 

^5^- 
^s^? 

*/_^ 

^ 

My 

1 

Per  Cent.  H2S04 
Fia.   18.     Specific  Gravities  of  Sulphuric  Acid 


80/18  =  4-44)  gives  the  percentage  of  free  »S03.  The  percentage  of  H2S04 
multiplied  by  80/98  (  =  0-8163)  gives  the  total  S03.  Similar  rules  may  be 
made  for  converting  any  of  these  three  expressions  into  any  other  : 

if  F  be  the  percentage  of  free  S03 

and  T  „  total  SO, 

and  H  „  H,S04 

then  F    =  4-444  (H  —  100) 

=   5-444  T  —  444 
and  T    =  0-8163  H 

=  01837  F  +81-63 
and  H    =  0-225  F  +  100 

=   1-225  T 

The  conversion  can  also  be  effected  by  means  of  the  stales  at  the  base  of  Fig.  17. 
All  countries  timing  the  war  are  Buffering  more  or  less  from  a  shortage  of 
sulphuric  acid  due  to  the  enormous  demands  and  the  disturbances  in  the 
supply  of  the  raw  materials.  In  Germany  the  cessation  of  the  imports  of 
pyrites  from  over-seas  appears  to  have  caused  considerable  trouble  in  spite  of 
the  fact  that  they  have  the  Belgian  acid  works  at  their  disposal  as  well  as 
their  own,  and  that  ores  can  be  obtained  from  Norway,  Hungary  and  Styria.1 
They  are  said  to  be  making  sulphuric  acid  from  calcium  sulphate  (gypsum) 
and  magnesium  sulphate  (Kieserite).1 

1  Set   F.  G.  Donnan,  Nature,  March  23,   l'.Uti.  p.  82. 

2  Chem.   Trade  Jour..   Nov.   27.    1916. 


CHAPTER   VIII 
NITRIC  ACID 

Manufacture  :  Recovery  of  nitrous  fumes  :  Storage  :  The  distillation  :  Nitre 
cake  :  Nitric  acid  from  the  atmosphere  :  Direct  oxidation  :  Cyanamide  process  : 
Serpek's  process  :  Haber's  process  :  Ostwald's  process  :  Properties  :  Specific 
gravities  :  Freezing-points  :  Boiling-points  :  Vapour  pressures 

Nitric  acid  is  usually  made  by  distilling  Chili  saltpetre  with  sulphuric  acid  Manufacture, 
in  large  iron  retorts.  Formerly  these  were  made  of  such  a  size  as  to  take  a 
charge  of  about  half  a  ton  of  sulphuric  acid  and  the  same  quantity  of  nitrate  : 
now  they  are  generally  made  to  take  twice  as  much  or  more.  Fig.  19  shows 
a  retort  somewhat  similar  to  those  used  for  the  Valentiner  system.  To  take 
a  ton  of  nitrate  the  retort  should  be  about  6  feet  in  diameter  and  6  feet  high  : 
it  must  not  be  too  small  on  account  of  the  danger  of  frothing  over  or  "  priming." 
Horizontal  cylindrical  stills  are  also  used. 

At  one  time  nitric  acid  was  only  made  of  about  60  per  cent,  strength,  but 
when  a  large  demand  for  stronger  acid  arose  for  the  manufacture  of  explosives 
it  was  found  that  there  was  no  real  difficulty  in  obtaining  nearly  the  whole 
of  the  acid  of  92  to  94  per  cent,  strength.  By  the  recovery  of  nitrous  fumes 
acid  of  60  per  cent,  strength  is  still  produced  :  formerly  it  was  sometimes  con- 
centrated by  distillation  with  sulphuric  acid,  but  now  it  can  be  utilized  directly 
mixed  with  C.O.V.  or  oleum. 

The  nitric-acid  vapours  were  formerly  condensed  by  air  cooling,  by  leading  condensers, 
them  through  a  large  number  of  stone- ware  jars  connected  by  stone- ware 
pipes,  but  this  system  was  inefficient  and  required  much  plant  and  space. 
The  reason  for  its  adoption  was  that  metal  condensers  could  not  be  used  because 
they  were  attacked  by  the  acid,  and  stone-ware  condensers  cooled  with  water 
would  have  cracked  with  the  changes  of  temperature.  But  with  the  improve- 
ments that  were  made  in  the  manufacture  of  earthen  and  stone-ware  tin's  has 
been  altered.  The  Guttmann  condensing  battery  has  been  much  used  (Fig.  20.) 
It  consists  of  a  number  of  vertical  stone-ware  pipes  immersed  in  a  tank  through 
which  water  circulates  ;  at  the  bottom  these  pipes  are  connected  by  cross- 
pieces  in  such  a  way  that  whilst  the  fumes  have  to  pass  up  and  down  the  pipes 
one  after  the  other,  the  condensed  acid  flows  along  from  one  cross-piece  to 
another  through  inverted  siphons  and  finally  to  the  storage  tank. 

107 


Iu8 


EXPLOSIVES 


In  the  Yalentiner  plant  (Fig.  21)  Btone-ware  coils  arc  used,  ami  these  are 
also  adopted  now  by  many  who  do  not  work  by  Yak-miners  system.  When 
first    introduced    there    were    frequent    breakages,    especially   at    the    upper 

extremity  where  the  coil  entered  the  water.     The  coils  could  he  repaired  by 
the  addition  of  a  piece  of  lead  pipe  joined  on.  for  the  Btrong  acid  ha-  hut  little 


Fig.    1!».      Xitri<-   Acid   Still 


action  upon  it.  Such  breakages  are  aoi  so  frequenl  now  :  they  can  he  avoided 
to  a  large  extent  by  not  immersing  the  firsl  coil  in  water,  but  cooling  it  by 
running  water  over  cloths  laid  on  the  coil.  Coils  can  now  he  obtained  made 
of  fused  silica  or  "  vitreosil  "  as  much  as  -  inch.  -  in  diameter  and  60  feel  long. 
These  are  much  more  resistant  than  stone-ware  and  can  be  repaired  when 
broken. 

The  principal  peculiarity  of  Dr.  Yalentiner-  system  is  that  the  distillation 


NITRIC   ACID 


109 


is  carried  out  in  vacuo.  At  the  end  of  the  series  of  condensers  and  jars  shown 
in  Fig.  21  there  is  a  vacuum  pump,  which  with  every  stroke  draws  in  some 
caustic  soda  solution  to  prevent  the  acid  fumes  attacking  the  metal  of  the 


c2 


'(UHWIWHF .■^'<|ow''»^T»y*w,>  ■w.v.rrM  fcrmK 


« 


n    r 


*/'*>+'m-Hi-jmr 


Fig.  20.     Guttmann's  Condensing  Battery  for  Nitric  Acid. 

pump  too  much.  The  large  number  of  small  washing  jars  is  also  to  absorb 
the  acid  fumes  as  far  as  possible  before  they  reach  the  pump.  The  advantages 
claimed  for  the  system  are  that  the  time  of  working  a  charge  is  much  shortened 
by  the  use  of  a  vacuum,  that  the  process  is  under  better  control,  and  that 


3800 
mm 


NITRIC   ACID  111 

there  is  less  breakage  of  coils  because  the  temperature  is  lower,  also  that  the 
acids  are  purer.  The  plant  is  well  designed  and  made,  and  consequently 
the  users  have  generally  found  it  satisfactory,  but  some  who  have  tried  working 
both  with  and  without  vacuum  state  that  they  can  achieve  equally  good  results 
at  the  ordinary  pressure,  and  with  less  complicated  appliances. 

In  the  Skoglund  process  the  gases  and  vapours  from  the  still  are  made  to 
pass  up  a  reaction  tower  and  then  up  a  condenser  instead  of  down.  The 
result  of  this  is  that  the  oxides  of  nitrogen  are  removed  almost  completely 
from  the  condensed  nitric  acid.  The  plant  is  used  in  many  explosives  factories 
in  North  America  and  in  several  French  dynamite  works.1 

Processes  for  the  continuous  or  semi-continuous  manufacture  of  nitric- 
acid  have  also  been  tried.2 

In  the  retort  a  certain  proportion  of  the  nitric  acid  is  always  reduced  Recovery  of 
through  various  causes  to  lower  oxides  of  nitrogen.  Some  of  this  is  dissolved 
by  the  strong  acid  in  the  condensers  and  is  an  objectionable  impurity.  In 
order  to  prevent  this  solution  taking  place  air  is  sometimes  drawn  over  the 
acid  whilst  it  is  still  warm,  and  this  carries  away  the  greater  part  of  the  lower 
oxides.  Whether  this  is  done  or  not,  there  is  always  some  nitrous  gas  that 
is  not  condensed  in  the  coils,  and  this  must  be  recovered  not  only  because 
it  is  valuable,  but  also  because  it  would  cause  a  nuisance.  After  passing 
through  the  condensing  coils,  therefore,  the  residual  gases  are  made  to  pass 
up  a  series  of  towers  filled  with  Lunge-Rohrmann  plates  or  Guttmann-Rohr- 
mann  balls.  A  jet  of  air  is  also  introduced  partly  to  draw  the  gases  along 
better  and  partly  to  oxidize  the  nitrous  gases.  These  consist  principally 
of  nitric  oxide  and  nitric  peroxide,  NO  and  N02  ;  the  former  is  rapidly  con- 
verted by  free  oxygen  into  the  latter,  so  that  then  there  is  only  NO,,  which 
when  it  comes  in  contact  with  water  forms  a  mixture  of  nitric  and  nitrous 
acids  : 

2N02  -f  H20  =  HN03  +  HN02 

But  nitrous  acid  is  only  sparingly  soluble  in  water  or  weak  nitric  acid,  and 
consequently  it  is  given  off  again  as  a  mixture  of  nitric  oxide  and  peroxide  : 

2HNO,  =  NO  +N02+H20. 

In  the  presence  of  oxygen  and  water  the  cycle  of  changes  then  recommences. 

Although  the  combination  of  the  nitric  oxide  with  oxygen  is  rapid,  the  reaction 

with  water  is  rather  slow,  and  consequently  a  considerable  amount  of  tower 

space  is  necessary  for  the  almost  complete  absorption  of  the  fumes. 

Storage  of 
Nitric  acid  of  00  to  05  per  cent,  strength  can  be  stored  either  in  large  stone-  nitric  acidj 

1  See  A.  F.  Otto,  S.S.,  1906,  p.  325  ;  E.  Wolff,  ibid.,  p.  373  ;  O.  Guttmann,  ibid., 
p.  376  ;   also  O.  Lunge.  Sulphuric  Arid  a»d  Alkali,  4th  ed..  vol.  i..  p.  178. 

2  See  Lunge,  loc.  cit.,  p.   154. 


112  EXPLOSIVES 

ware  vessels  or  in  iron  tanks  lined  "with  chemical  lead.  The  action  of  the 
a<id  on  the  lead  is  very  slight,  and  such  tanks  last  for  years  before  they  require 
to  be  rt  lined.  For  weaker  acid,  stone-ware  and  glass  are  practically  the  only 
materials  that  are  available.  The  maximum  theoretical  strength  of  acids 
running  from  a  tower  of  this  kind  is  that  of  the  constant  boiling  mixture  of 
nitric  acid  and  water,  which  contains  68  per  cent,  of  the  former  and  has  a 
specific  gravity  of  1-41  (42°  B.).  but  generally  it  is  considerably  weaker  than 
this  and  has  a  specific  gravity  of  about  L-38,  corresponding  to  (11  per  cent. 
HN08.  If  a  series  of  towers  is  installed,  the  weak  acid  from  one  should  be 
raised  continuously  and  made  to  How  down  the  next  in  the  opposite  direction 
to  that  of  the  gases. 

The  nitrate  is  dried  by  being  spread  on  iron  plates  on  the  top  of  a  retort, 
whilst  a  previous  charge  is  being  worked.  It  is  passed  in  through  the  man- 
hole in  the  top  of  the  retort,  sulphuric  acid  is  run  in,  and  the  lid  of  the  man- 
hole is  closed  and  luted  down  with  clay  or  a  mixture  of  asbestos  powder  and 
water-glass.  Theoretically,  1153  parts  of  H2804  are  required  to  convert  1 
part  of  NaNOj  into  NaHS()4  :  in  practice  it  is  usual  to  add  rather  less.  1-04 
to  108  parts,  so  that  the  nitre  cake  contains  about  20  per  cent,  of  the  neutral 
sulphate  X.i  , SO,.  To  use  too  much  acid  would  not  only  involve  a  waste  of 
1  his  substance,  but  would  make  the  bisulphatc  too  soft  and  acid,  and  therefore 
difficult  to  handle.  It  is  always  well  to  add  a  little  weak  nitric  acid  to  the 
charge  or  some  weaker  sulphuric  acid,  or  waste  acid  from  the  manufacture  of 
nitro  cotton.  Iti  this  way  not  only  is  some  of  the  weak  acid  worked  up.  but 
the  yield  of  good  nitric  acid  is  increased.  If  the  charge  is  practically  free  from 
water,  some  of  the  nitric  acid  in  the  retort  is  converted  into  nitric  anhydride, 
which  breaks  down  very  readily  into  nitric  peroxide  and  oxygen,  and  produces 
a  dark  acid.  The  charge  having  been  introduced,  the  fire  is  lit  and  the  retort 
is  gradually  heated.  If  working  in  vacuo  under  a  pressure  of  7  inches  of  mer- 
cury, acid  begins  to  come  over  at  about  100°  ('.  ;  if  at  atmospheric  pressure, 
somewhat  higher.  As  the  distillation  becomes  more  active,  the  heat  must  be 
moderated  to  prevent  priming.  The  first  runnings  are  liable  to  contain  a 
considerable  proportion  of  hydrochloric  acid  and  other  impurities  as  well  as 
much  nitrous  acid.  Therefore,  if  acid  of  good  quality  be  required  the  first 
portion  should  be  collected  separately  and  not  added  to  the  main  bulk,  or  a 
current  of  air  should  be  drawn  over  the  still  warm  acid  as  mentioned  above. 
The  last  runnings  are  liable  to  be  rather  weak,  so  that  if  acid  of  the  highest 
strength  be  required  they  also  should  be  collected  separately. 

To  work  off  a  charge  of  nitric  acid  takes  about  ten  hours,  but  it  is  claimed 
that  in  the  latest  Valentiner  plant  it  can  be  done  in  four  and  a  half  hours. 

When  the  charge  is  finished,  and  whilst  the  contents  of  the  retort  are 
still  hot.  the  plug  in  the  opening  at  the  bottom  is  removed,  and  the  residue 
in  the  retort  is  allowed  to  run  out  through  a  removable  gutter  into  a  trolley 


NITRIC   ACID  113 

or  a  shallow  cast-iron  trough.  The  latter  is  preferable,  as  the  "  nitre-cake  " 
is  easier  to  break  up  if  it  is  in  a  thin  layer.  This  is  done  by  means  of  a 
crowbar  or  sledge-hammer,  and  the  broken  cake  is  removed  to  a  convenient 
place  of  storage  until  it  can  be  disposed  of.  Nitre-cake  consists  mostly  of 
sodium  bisulphate  with  some  neutral  sulphate,  a  fair  amount  of  moisture 
(especially  if  it  has  been  exposed  to  the  atmosphere  long  or  has  been  rained 
on),  a  little  nitric  acid,  and  other  impurities. 

It  is  generally  used  either  for  making  superphosphate  manure  or  hydro- 
chloric acid  and  sodium  sulphate  ;  in  out-of-the-way  districts  its  disposal 
is  often  a  matter  of  difficulty,  as  its  value  is  small,  and  it  is  troublesome  to 
transport  on  account  of  its  corrosive  qualities.  At  the  present  time  (1916) 
these  difficulties  are  much  accentuated  by  the  enormous  increase  in  the 
manufacture  of  nitric  acid  for  the  production  of  military  explosives,  and 
fresh  outlets  are  being  sought  for  this  by-product.1  J.  Grossmann  2  has 
worked  out  a  process  for  treating  the  nitre-cake  with  calcium  sulphite  and 
lime  and  so  converting  it  into  caustic  soda  and  sodium  sulphate.  As  there 
is  a  great  demand  for  sulphuric  acid,  nitre-cake  solution  is  being  used  for 
many  purposes  where  formerly  oil  of  vitriol  was  employed.  Apparently  it 
is  being  used  successfully  in  the  wire  making  industry  and  for  various  purposes 
in  connexion  with  textiles.3  Proposals  to  use  it  for  the  manufacture  of 
ammonium  sulphate  have  been  adversely  criticised.4  Other  uses  are  : 
acidifying  the  phenolates  obtained  in  the  working  up  of  coal  tar,  acidifying 
soap  stock,  preparing  sulphates,  treating  rubber  scrap  and  pickling  iron  and 
steel. 

During  the  last  ten  years  great  advances  have  been  made  in  the  manu-  Nitric  acid 

facture  of  nitrogen  compounds  from  the  nitrogen  of  the  atmosphere.     Until  Irtom  thv 

,        .  •    -i        i  atmosphere 

recently  the  materials  thus  made  were  used  almost  entirely  as  fertilizers  : 

for  the  manufacture  of-  explosives  Chile  saltpetre  remained  almost  the  sole 

source  of  nitrogen.     After  the  outbreak  of  war  in  August  1914  the  Central 

European  Powers  were  cut  off  from  Chile,  and  in  Germany  energetic  steps 

were  taken  to  develop  the  manufacture  of  nitrates  and  nitric  acid  from  the 

atmosphere.     Rapid  development  of  this  industry  was  possible  as  the  pioneer 

work  had  already  been  done. 

Many  different  processes  have  been  proposed  and  several  are  in   actual 

operation  on  a  large  scale.     They  may  be  divided  into  two  classes  :    those 

in  which  the  oxygen  and  nitrogen  are  made  to  combine  together  directly, 

and  those  in  which  ammonia  is  first  formed  and  then  oxidized  to  nitric  acid 

by  Ostwald's  method.     The  advantage  of  the  latter  process  lies  in  the  fact 

1  J.  Soc.  Chem.  Ind.   1915,  p.  1121,  1916,  p.  77. 

2  Ibid.,  1916,  p.  155. 

3  Chem.  Trade  Jour.,   Jan.  8,  1916,  J.  Soc.  Chem.   Ind.,   1916,  p.  109. 

4  Chem.  Trade  Jour.,   Mar.  4,  1916,  Mar.  11,  1916,  pp.  233,  235. 

VOL.  I,  R 


114 


EXPLOSIVES 


that  ammonia  is  more  easily  produced  than  nitric  oxide,  as  it  is  formed  with 
evolution  of  heat,  whereas  nitric  oxide  i>  an  endothermic  compound  : 

X    —  3H  ,  =  2XH  ,  —  24  I  alories 
X.         0,       2N0    -43  2       .. 

And  the  oxidation  <>f  the  ammonia  is  also  an  exothermic  reaction,  as  the 

conversion  of  the  hydrogen  into  water  supplies  the  necessary  heat. 

Processes  for  the  direct  oxidation  of  nitrogen  were  those  first  worked 
out  commercially.  These  require  temperatures  of  several  thousand  degn  I  s, 
which  can  only  be  obtained  by  means  of  an  electric  arc.  Air  is  passed  through 
the  arc  and  then  rapidly  cooled  to  prevent   the  nitric  oxide  decomposing 

.  into  oxygen  and  nitrogen.  About  2  per  cent,  of  nitric  oxide  is  obtained, 
and  this  is  converted  into  dilute  nitric  acid  by  passing  it  up  tower-  down 
which  water  i-  flowing.  The  various  processes  differ  in  the  means  taken 
to  pass  a  sufficiently  large  volume  of  air  through  the  arc  and  then  cool  them. 
In  the  Birkeland-Eyde  furnace  an  alternating  arc  is  made  to  spread  out  fan- 
wise  by  mean-  of  electro-magnets.  In  the  Pauling  furnace  the  arc  is  V-shaped, 
due  to  the  nse  of  long  electrodes  inclined  to  one  another  at  an  angle.  And 
in  the  Schdnherr  furnace  a  spiral  flame  is  obtained  by  1  (lowing  air  through 
inclined  hole-  in  a  tube  forming  one  of  the  electrodes. 

The  consumption  of  energy  in  these  processes  is  about  60  kilowatt-hours 

kilogramme  of  nitrogen  fixed.  Consequently  they  can  only  be  worked 
at  a  profit  where  there  is  a  very  large  Bupply  of  cheap  water  power,  and  Norway 
is  the  principal  seat  of  the  industry.     The  emerging  air  contains  about  2 

ent.  of  nitric  oxide,  and  this  is  mostly  converted  into  weak  nitric  acid 
by  ]     --     _   it  up  towers  down  which  water  is  flowing. 

The  4<i  per  cent,  nitric  acid  thus  obtained  could  be  concentrated  by  distilla- 
tion with  sulphuric  acid,  but  as  nitric  acid  is  difficult  to  transport  it  is  usually 
converted  into  calcium  nitrate  by  neutralizing  it  with  limestone  and  milk 
of  lime  and  evaporating  down.  The  product  thus  obtained  is  known  as 
Norwegian  saltpetre  and  is  osed  as  a  fertilizer.  Ammonium  nitrate  is  also 
made  by  neutralizing  with  ammonia  liquor.  And  -odium  nitrite  is  obtained 
in  the  last  scrubbing  towers  by  miming  sodium  carbonate  solution  down 
them.  It  i-  -aid  that  at  a  Swiss  works  controlled  by  the  Elektrochemische 
Werke  in  Bitterfeld   the  nitric  oxide  i-  allowed  to  oxidize  to  peroxide,  which 

covered  in  the  form  of  -now  by  Btrongly  cooling  the  air.1     This  is  then  to 

llowed   to  melt  and  sent  into  Germany  in  tank  wagons,  and  there  made 

into  nitric  acid  by  treatment   with  air  and  water.     Nitric  peroxide  frees  - 

at  about  10°C.  and  boil-  at  about  26   ' '.  :  it  i-  far  less  corrosive  than  nitric  acid. 

The  manufacture  of  calcium  cyanamide  was  worked  out  by  Frank  and 

.  and  i-  now  the  basis  of  a  wh«.'  of  important  chemical  industries. 

1  Badermam.     S     5      L914,  |».  527. 


NITRIC   ACID  115 

It  is  made  from  calcium  carbide,  which  is  manufactured  by  heating  lime 
and  anthracite  coal  together  in  an  electric  furnace  at  about  3000°  C.  The 
carbide  is  powdered  and  placed  in  a  retort  which  can  be  heated  externally 
by  means  of  a  gas  or  electric  furnace,  and  nitrogen  is  passed  in.  The  nitrogen 
is  now  generally  obtained  by  liquefying  air  and  fractionally  distilling  it. 

CaC2       +        Na      =        CaN2C       +       C 

Calcium  carbide  Nitrogen  Calcium  cyanamide  Graphite 

The  reaction  starts  at  about  800°  C.  and  proceeds  with  the  evolution  of 
heat.  The  temperature  must  not  be  allowed  to  rise  above  1400°  C,  or  some 
of  the  cyanamide  will  be  reconverted  into  carbide.  The  cyanamide  is  used 
on  a  large  scale  directly  as  a  manure,  and  also  as  a  source  of  ammonium 
sulphate  which  is  applied  for  the  same  purpose.  It  is  also  converted  into 
cyanides,  guanidine,  dicyandiamine  and  other  compounds.  For  the  con- 
version of  cyanamide  into  ammonia  it  is  treated  in  a  closed  tank  with  steam 
under  pressure  in  the  presence  of  water  and  alkali.  The  reaction  is  exothermic 
and  proceeds  for  a  time  after  the  steam  has  been  shut  off.  When  the  steam 
has  been  applied  three  times  the  yield  is  almost  theoretical.1  The  cyanamide 
process  is  apparently  the  one  which  the  German  Government  is  developing 
most  largely  for  the  production  of  nitric  acid  for  the  manufacture  of  explosives. 
The  consumption  of  power  is  considerably  less  than  in  the  direct  oxidation 
methods  :  about  24  kilowatt-hours  per  kg.  of  fixed  nitrogen  as  compared 
with  60,  and  the  raw  materials  required,  coal,  lime,  nitrogen  and  steam  are 
all  cheap.  Consequently  the  process  can  be  worked  wherever  power  can 
be  produced  at  a  moderate  cost. 

In   this   process   bauxite,    a   natural   crude    alumina,    is    converted   into  Serpek's 
r  ...     process, 

aluminium  nitride  by  heating  it  with  coal  in  an  atmosphere  of  nitrogen  in 

an  electric  furnace  at  1700°  to  1800°  C. 

A1203  +  3C  +N2  =  2A1N  +  3CO  —243  Calories 

Producer  gas,  a  mixture  of  nitrogen  and  carbon  monoxide,  is  used  as  the 
source  of  nitrogen. 

The  nitride  is  then  treated  with  a  solution  of  caustic  soda,  which  converts 
it  into   ammonia   and   sodium   aluminate 

A1N  +  3NaOH  =  NH3  +  Na3A103. 

Many  of  the  impurities  of  the  bauxite  are  eliminated  during  these  operations 
and  consequently  the  aluminate  can  be  used  for  the  manufacture  of  aluminium. 
The  power  required  is  only  about  12  kilowatt-hours  per  kg.  of  fixed  nitrogen, 
but  bauxite  being  a  comparatively  expensive  material  the  process  can  only 
be  used  in  combination  with  aluminium  works. 

1  gee  W.  S.  Landis,  J.  Ind.  Eng.  Chem.,   1916,  p.   156, 


116  EXPLOSIVES 

Professor  Haber  worked  out  his  method  for  the  direct  production  of 
ammonia  from  nitrogen  and  hydrogen  by  a  thorough  study  of  the  physical 
chemistry  of  the  reaction.  The  process  has  been  taken  over  and  developed 
commercially  by  the  powerful  Badische  Anihn  und  Soda  Fabrik.  The  mixture 
of  gases  is  passed  at  high  temperature  and  pressure  over  a  solid  contact 
substance,  which  promotes  the  reaction.  Osmium  and  uranium  are  some 
of  the  materials  that  have  been  u>ed  for  this  purpose,  but  apparently  upon 
i>  more   satisfactory  in  some  respects.     The  temperature  i>  maintained  at 

to  700*  C.  and  the  pressure  at  about  2<>n  atmospheres.  The  g 
circulated  round  a  closed  circuit  with  heat  and  cold  regenerating  appliai 
rir>t  over  the  heated  contact  substance  and  then  through  a  cooler,  where 
the  temperature  i>  reduced  to  —  60c  or  —  To  ('..  which  causes  the  ammonia 
parate  as  a  liquid.  In  each  circuit  about  6  per  cent,  of  ammonia  is  funned 
and  liquefied.  This  process  i-  Baid  to  require  power  only  to  the  extent  of 
2  kilowatt-hours  per  kg.  of  fixed  nitrogen.,  but  very  great  difficulties  had 
t"  be  overcome  before  plant  could  be  made  to  work  satisfactorily  at  the 
cnormoib  pressure  required.     The  low  cost  for  power  is  also  compensated 

-  .me  extent  by  the  comparatively  high  cost  of  hydrogen.     It  is  obtained 
either  by  the  electrolysis  of  water  or  from  producer  gas  by  liquefying  out 
the  carbon  monoxide  and  purifying  it.     Haber's  process  is  apparently  being 
loped  by  the  (ierman  Government  in  addition  to  the  cyanamide  pro 

If  ammonia,  together  with  oxygen  or  air.  be  passed  over  a  suitable  contact 
Bubstance  it  i-  converted  into  oxides  of  nitrogen,  from  which  nitric  acid  can 
be  obtained.  Thi>  has  long  been  known,  but  about  1900  Profes>or  Ostwald 
commenced  to  investigate  the  most  favourable  conditions  for  the  reaction. 
He  found  that  platinum  was  a  suitable  catalyzer,  but  it  should  not  be  in  too 
fine  a  condition,  and  the  ,Lra-e-  Bhould  be  passed  over  it  very  rapidly,  otherwise 
the  ozidi  -  of  nitrogen  formed  are  further  decomposed  into  nitrogen  and 
-  Long  a  the  ammonia  was  practically  only  a  by-product  in  the 
destructive  distillation  of  coal,  the  amount  available  was  too  small,  and  the 
other  demands  for  it  too  great,  to  make  this  process  very  successful  or 
remunerative.  But  with  the  introduction  of  synthetic  ammonia,  made  by 
the  cyanamide  and  Haber's  processes,  the  condition-  were  altered  entirely. 

The  ammonia  mixed  with  10  volumes  of  air  is  passed  through  a  plug 
of  platinum  >poiiLr<-  2  cm.  thick  at  a  temperature  of  300  C.  at  such  a  velocity 
that  it  remains  in  contact  with  the  platinum  only  0-002  seconds.  About 
85  per  cent,  of  the  ammonia  i-  oxidized,  not  to  nitric  arid,  which  cannot 
exist  at  this  temperature,  but  to  nitric  oxide,  which  promptly  combines 
with  further  oxygen  to  form  nitric  peroxide.  The  gases  pa—  up  a  tower 
where  t;  et   nitric  acid  :    here  the  water  formed  in  the  reaction 

2NH,  -f  2JO,  =  2N0  -f3H;,0  +  106-8  Caloi 


NITRIC  ACID 


117 


is  condensed  and  with  the  nitric  peroxide  and  further  oxygen  yields  nitric 
acid,  which  is  obtained  from  the  tower  with  a  strength  of  about  58  per  cent. 
Instead  of  platinum  other  catalyzers  have  been  proposed,  a  mixture  of  ceria 
and  thoria  by  Frank  and  Caro,  burnt  pyrites  by  F.  Bayer  &  Co.,  etc. 

The  development  of  these  processes  for  the  synthetic  production  of  nitric 
acid  has  been  of  great  value  to  Germany  in  the  war,  in  fact,  she  probably 
could  not  have  continued  the  struggle  without  them,  for  the  stocks  of  Chile 
saltpetre  must  have  been  exhausted  after  about  a  year. 

The  concentrated  acid  has  very  little  action  upon  metals.  The  more  Properties 
dilute  acid  acts  energetically  on  all  the  common  metals  ;  if  the  acid  be  quite  mtric  acu 
free  from  nitrous  acid  there  is  no  action,  but  as  commercial  acid  always 
contains  some  nitrous  this  is  not  a  matter  of  great  practical  importance.  The 
concentrated  acid  is  not  very  stable  and  tends  to  decompose  into  NO  2,  oxygen 
and  water.  The  nitric  peroxide  dissolves  readily  in  the  strong  acid,  which 
consequently  always  has  a  more  or  less  reddish  colour.  In  weaker  acid  the 
solubility  is  less,  and  nitric  acid  of  1-4  specific  gravity  dissolves  very  little 
of  the  peroxide. 

The  Tables  of  Lunge  and  Rey  superseded  the  earlier  inaccurate  ones,  but  JjJJjJJ^ 
the  more  recent  determinations  of  Veley  and  Manley  x  are  more  numerous. 
The   figures   have  been  interpolated  graphically,  those  above    63  per    cent, 
by  Veley  and  Manley,  those  below  by  myself,  and  are  given  in  the  Table 
on  p.  118. 

The  influence  of  nitric  peroxide  on  the  specific  gravity  is  considerable 
and  has  been  ascertained  by  Lunge  and  Marchlewski  2  for  an  acid  having 
the  specific  gravity  1-496. 


Per  cent.  N204 

Alteration  of  sp.  gr. 

Per  cent.  N204 

Alteration  of  sp.  gr. 

0-25 

•0005 

5-0 

•0323 

0-50 

•0008 

6-0 

•0395 

0-75 

•0015 

7-0 

•04()5 

100 

•0030 

8-0 

•0533 

1-25 

•0048 

9-0 

•0600 

1-50 

•0068 

100 

•0660 

L-75 

•0078 

110 

•0730 

200 

•0105 

120 

•0785 

3-0 

•0180 

12-75 

•0835 

40 

■0253 

1  Phil.  Trans.  A.,  vol.  191,  p.   365  (1898),  and    Proc.  Hoy.  Soc,  1901,  p.  86,  and  J. 
Soc.  Chem.  Ind.,  1903,  p.   1227. 

2  A ng.,   1892,  p.   10. 


118 


EXPLOSIVES 


The  figure  in  the  second  column  isl  subtracted  from  the  specific  gravity 
before  ascertaining  the  strength  of  the  nitric  acid  by  means  of  the  specific 
gravit  v  Table.  The  amount  of  lower 
oxide  is,  however,  often  caleulat- 
nitrous  acid.  The  figures  in  the  first 
column  of  the  above  Table  must  be 
multiplied  by  -519  to  give  the  cor- 
responding amounts  of  nitron-  acid 
in  accordance  with  the  equation  : 
NTtO,  +  H20  =  HX<»  +HNO,. 
The  freezing-points  of  mixtures 
of  nitric  acid  and  water  are  Bhown 
in  Kg.  '22.    which  u  on   the 

determination-  of  Kii>ter  and  Kre- 
mann.1  It  will  be  seen  that  all  mix- 
tures solidify  at  temperature-  con- 
siderably   below    the    freezing-point 


Pig.  22. 


Freezing-points  of  Xitri 


100  Mol% 
HS03 


Specifk     Cra 

VXEEBS    OF    XlTRIC    ACID    AT    15"    4:    IX    YacCO 

(Vel^y  and  Hanky) 

Specific 

P^r                       Difference               Specific 

Per  cent. 

Difference 

gravity 

HX03                 for  1 

gl     v:ty 

HXO: 

for  1 '  C. 

1-000 

•0001 

1-21 

42-7 

•001" 

I -010 

1-90                 4)002 

1-280 

44-:; 

•11 

1-020 

3-8                   ■ 1 

1  290 

• 

011 

1  -030 

5-6                   4)002 

1-300 

47-4 

Oil 

1-040 

•0003 

1-310 

'11 

H  ■" 

90                   -0003 

1-32 

•0012 

1-060 

10-1                   4)004 

1-3! 

52-1 

•0012 

1<- 

12-4                   4)004 

1-340 

53-8 

•0012 

1  080 

144)                   4M 

1  •:;.- 

•0013 

1-090 

15-6 

4)005 

1-34 

•13 

MOO 

17-2 

•0" 

1-310 

013 

1-110 

18-9 

•o<> 

1-380 

61-4 

014 

1-110 

-     ' 

•0006 

1-390 

53-1 

•0014 

1130 

224) 

4)006 

1-400 

•0014 

M40 

-     ■ 

•0006 

1-41" 

J 

•0016 

1150 

21 

4M"  " 

1-4. 

•00  lr, 

1160 

_     ■ 

4)001 

1-4 

724) 

•ooi.-. 

Ml 

001 

1-44" 

74-5 

•001". 

1180 

_       3 

4)001 

1-41 

71 

016 

1190 

310 

•0008 

1  460 

80-3 

4)016 

1-200 

•0009 

1-47" 

a 

016 

M10 

33-8 

•0009 

1-480 

86-3 

•0017 

1:. 

•001" 

1-490 

89-6 

•0017 

1-230 

36-8 

•001" 

1  .-,oo 

•17 

1-240 

38-2                    0010 

1-510 

97-8 

018 

1-: 

4)010 

1-52 

99-8 

•Cm.. 

1  260 

41  1                     -0010 

1  Z.  j.  anorg. 

f  ..   1904,  p.  2 

1. 

NITRIC  ACID 


119 


of  water.  In  the  first  portion  of  the  curve  ice  separates  out,  in  the  second 
crystals  of  HN03,3H20,  in  the  third  HN03,H20,  and  in  the  last  solid 
nitric  acid. 

Pure  nitric  acid  boils  at  about  86°  C.  under  atmospheric  pressure,  and  Boiling  p( 
at  21-5°  under  a  pressure  of  24  mm.  When  water  is  added  to  the  acid 
the  boiling-point  increases  until  it  reaches  a  maximum  at  about  68  per  cent. 
HN03,  and  then  falls  again.  If  acid  either  stronger  or  weaker  than  this 
be  evaporated  or  fractionally  distilled,  the  composition  tends  to  approach 
this  percentage,  and  when  it  is  reached  the  mixture  distils  unchanged.  The 
composition  of  the  constant  boiling  mixture  depends  upon  the  pressure, 
however;  in  vacuo  a  mixture  containing  66-3  molecular  per  cent.  HN03 
boils  at  13°,  giving  a  distillate  of  the  same  composition  ;  under  735  mm. 
pressure  the  constant  boiling  mixture  contains  68-0  per  cent,  and  boils  at 
120-5°  ;    under  1220  mm.  the  composition  is  68-6  per  cent.1 

Saposhnikoff  has  made  a  few  determinations  of  the  vapour  pressures  of 
nitric  acid  at  15°  C.2 


Per  cent. 
HNO3 

Yap.  pres.  15°  C. 
mm. 

Per  cent.  N  in 
vapour 

Molecular  per  cent. 
HN03 

98-0 

46-2 

23-7 

93-5 

92-9 

42-6 

23-5 

790 

88-6 

29-7 

230 

68-7 

821 

16-6 

22-6 

56-5 

781 

9-4 

22-5 

50-0 

65-3 

1-9 

19-3 

34-7 

With  reference  to  the  third  column  of  the  above  Table  it  is  to  be  borne  in  Vapour 
mind  that  HN03  contains  22-2  per  cent,  N.     It  is  therefore  evident  that  pressures 
the  vapours  from  the  nitric  acid  contain  nitric  peroxide  or  nitric  anhydride, 
which  have  30-6  and  25-9  per  cent.  N  respectively. 

1  Roscoe,  Lieb.  An.,  1860,  pp.  116,  203.     See  also  H.  J.  M.  Creighton  and  J.  H.  Githens, 
J.  Franklin  Inst.,   1915,  p.   161. 

-  Z.  phya,  C,   1905,  pp.   53,   225. 


CHAPTER   IX 
MIXED   AND   WASTE   ACIDS.     MANIPULATION 

Mixed  acid  :    Mixing  the  acids  :    Properties  of  mixed  acids  :    Specific  Gravities  : 
Vapour   ptooomce         '     -te   acid:     Gun-cotton    waste    acid:     Xitro- glycerine 
waste  acid  :     Xitro -compound  waste  acid  :    Denitration  plant  :    Manipulation 
of  acid<  :    Materials  ;    Raising  acid  :    Oleum 

Nitration,  whether  of  glycerine  or  cotton  or  an  aromatic  compound.  Buch 
as  toluene,  is  always  carried  out  with  a  mixture  of  sulphuric  and  nitric 
acids,  and  not  with  nitric  acid  alone,  for  even  the  strongest  nitric  acid 
not  act  well  by  itself.  One  of  the  main  functions  of  the  sulphuric  acid  is 
to  combine  with  the  water  that  is  formed  during  the  reaction  and  prevent  it 
diluting  the  nitric  acid,  bnt  it  appeals  probable  that  it  also  take*  an  active  part 
in  the  reaction,  and  that  to  some  extent  at  any  rate  it  combines  first  with  the 
substance  to  be  nitrated  to  form  a  sulphuric  ester  or  sulphonic  acid,  and  that  it 
i-thi-  which  is  afterwards  acted  upon  by  the  nitric  acid.  In  the  presence  of 
sulphuric  acid  the  nitration  is  not  only  more  complete  but  also  more  rapid. 

The  two  acids  are  mixed  together  in  iron  tanks.  For  work  on  a  moderately 
large  Bcale  old  steam-boilers  can  be  used  for  this  purpose,  the  fire  tubes  being 
removed  and  the  openings  closed  by  riveting  on  plates.  For  work  on  a  I  s 
scale  it  i-  better  to  have  special  tank-  built,  large  enough  to  hold  aev< 
day-'  supply  of  mixed  acid.  The  best  form  i>  a  cylinder  with  it-  axis  vertical. 
the  height  being  Bomewhat  less  than  the  diameter.  Passing  through  the 
cover  there  should  be  a  shaft  to  which  arms  are  attached.  >o  that  by  rotating 
the  Bhaft  the  contents  of  the  tank  can  be  stirred.  When  the  mixing  is  carried 
out  in  small  boilers  the  agitation  of  the  liquid  usually  has  to  be  effected  by 
blowing  air  through  it.  which  canst  ght  1"--  of  nitric  acid. 

When  nitric  acid  is  added  in  small  quantities  to  sulphuric  acid,  the  specific 
gravity  at  tir-t  rises  Bharply  in  >pite  of  the  fact  that  nitric  acid  has  a  lower 
density  than  sulphuric.  The  specific  gravity  attain-  a  maximum  and  then 
falls  again,  a-  i-  Bhown  in  Fig.  2:i  and  in  the  Table  :  on  p.   21.     Saposhnikoff  2 

1  Mar-hall.  J.    3oC.  (  1902,  p.    1508. 

2  Ztlttrh.  PhyaikaL  Chem.,   1904,  pp.   4'.'.  •  .'.<:  :     1905,  pp.  53,  226, 

120 


MIXED   ACID 


121 


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Fig.  23.     Specific  Gravities  of  ]\fixed  Acids  (Marshall; 


HN(>3 

Sp.  gr.  1 8°/  1 8° 
in  air 

HN()3 

Sp.  gr.  18°/18° 
in  air 

Per  cent. 

Per  cent. 

0-00 

1-8437 

22-51 

1-8215 

0-57 

'      1-8456 

25-5(5 

1-8112 

105 

1-8476 

27-29 

1-8053 

4-67 

1-8586 

32-53 

1-7863 

717 

1-8618 

37-0:! 

1-7700 

7-37 

1-8620 

39-49 

1-7601 

i  •  /.) 

1-8619 

57-78 

1(1879 

910 

1-8605 

72-89 

1-6227 

11-33 

1-8557 

90-76 

1  .->408 

12-71 

1  -8520 

98-19 

1-5080 

16-52 

1-8414 

100-00 

1-5009 

122 


EXPLOSIVES 


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40 


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Molecular   Percentage   Sulphuric    Acid  • 

."-niT  Pre--  Sulphuric  Acid  with  Nitric 

Acids  of  Various  Strenp 


100 


p        f  nitric  acid,  per  cent. 
•ular 


I. 

980 

93-5 

II. 

. 

. 

III. 

. 

. 

IV. 

. 

35-4 

v. 

30-0 

•22-2 

MIXED  ACID  123 

has  obtained  similar  results.     The  following  are  two  maximum  specific  gravities 
observed  by  him  with  mixtures  containing  different  amounts  of  water  : 

Sp.  gr.  25°/25°  1-8810  1.865 

Sulphuric  acid        .  .  .  89-32  per  cent.  .  .  89-94  per  cent. 

Nitric  acid    .  .  .  1013  ..  6-57 

Water -28      „  . .  3.49 

Oxide  of  nitrogen.  .  .  -27 

The  second  of  the  above  is  almost  identical  both  in  composition  and  density 
with  the  maximum  observed  by  Marshall.  From  the  results  of  his  measure- 
ments of  the  vapour  pressures  Saposhnikoff  came  to  the  conclusion  that 
there  is  little  or  no  combination  of  the  two  acids  to  form  complex  molecules 
and  he  ascribed  these  high  specific  gravities  to  the  formation  of  nitric 
anhydride,  N205.  But  as  this  substance  has  a  specific  gravity  of  only  1-64, 
the  explanation  does  not  appear  sufficient,  It  seems  possible  that  the  high 
densities  are  due  to  some  reversible  reaction  taking  place  between  the 
sulphuric  and  nitric  acids. 

Saposhnikoff 's  determinations  of  the  vapour  pressures  of  mixed  acids  are  Vapour 
shown  in  the  curves  in  Fig.  24,  in  which  mm.  of  pressure  are  plotted  against  Pressures- 
the  molecular  percentage  of  sulphuric  acid  in  the  mixtures.  The  sudden  fall 
at  the  left  end  of  curve  /  is  due  to  the  fact  that  the  nitric  acid  used  contained 
about  0-9  per  cent,  of  nitric  oxide,  which  ia  very  volatile  as  compared  with 
nitric  acid.  When  a  little  sulphuric  acid  was  added  it  combined  with  this 
to  form  nitro-sulphuric  acid,  which  is  not  volatile.  Through  the  greater  part 
of  its  course  this  curve  is  practically  straight :  if  the  acids  had  been  quite 
anhydrous  and  free  from  impurities  it  would  probably  have  been  straighter 
With  acids  containing  water  the  addition  of  sulphuric  acid  increases  the 
vapour  pressure,  because  it  combines  with  the  water  and  decomposes  the 
compound  of  nitric  acid  and  water.  The  pressure  is  at  a  maximum  when 
there  is  nearly  a  molecule  of  sulphuric  acid  for  each  one  of  water  :  then  it 
falls  again.  These  vapour-pressure  curves  are  also  given  in  another  form 
in  Fig.  28,  which  shows  the  connexion  between  the  vapour  pressure  and  the 
degree  of  nitration  of  cotton.  That  there  should  be  such  a  connexion  might 
have  been  anticipated,  as  the  activity  of  a  substance  in  solution  generally 
increases  when  the  vapour  tension  increases,  but  mixtures  with  equal  vapour 
pressures  do  not  by  any  means  always  produce  nitro-cottons  with  equal 
amounts  of  nitrogen,  as  a  careful  examination  of  the  diagram  will  show. 

WASTE  ACID 

The  waste  acid  from  the  manufacture  of  nitro-cotton  is  usually  revivified  Gun-cotton 
by  the  addition  of  strong  sulphuric  and  nitric  acid,  and  used  again,  but  if  waste  acid- 
the  whole  quantity  were  strengthened  up  in  this  way  each  time  the  quantity 


124  EXPLOSIVES 

would  steadily  increase.  It  is  therefore  necessary  to  discard  some  of  the 
waste  acid.     The  quantity  of  waste  acid  produced  in  the  displacement  pr 

for  the  manufacture  of  gun-cotton  i>  more  than  in  the  older  methods,  for  the 
recovery  of  the  waste  acid  is  much  more  complete  and  Borne  of  it  becomes 
diluted  with  the  water  used  for  the  displacement.      "When  nitrated  by  the 

Abel  process  or  in  centrifugals  a  considerable  amount  of  acid  remain-  in  the 
gnn-COtton  after  the  hulk  ha-  been  removed  in  the  centrifugal-.  If  oleum 
of  60  to  70  per  cent,  be  used  together  with  nitric  acid  of  about  '.•:>  per  cent, 
strength,  the  fresh  acid  does  not  bring  the  volume  of  add  much  above  its 
original  bulk,  for  it  does  not  much  exceed  what  is  lost  in  the  manner  just 
mentioned,  together  with  the  nitric  acid  actually  consumed  in  the  nitration. 
En  small  factories,  which  do  not  possess  the  plant  for  working  up  the  waste 
acids  again,  this  is  a  great  advantage  because  only  a  very  inadequate  price 
can  be  obtained  for  the  waste  acid  if  it  has  to  be  sold.  Where  the  nitric- 
acid  can  be  recovered  on  the  spot  it  is  more  usual  to  use  oleum  of  2<>  - 
per  cent,  strength. 

These  revivified  acids  are  little,  if  at  all.  le>s  efficient  than  new  acid,  at 
any  rate  for  the  manufacture  of  the  more  insoluble  varieties  of  nitaro-cellulose. 
The  organic  impurities  formed  in  the  nitration  process  apparently  either  pass 
away  in  the  nitrated  product  and  so  eventually  into  the  waters  used  for  the 
purification,  or  else  are  oxidized  completely  away  by  the  acid  if  they  have 
passed  into  solution.  The  quantity  of  organic  impurity  in  the  acids  remains 
-mall  therefore  ;    but  Will  found  oitro-sugars  in  the  acid-. 

The  portion  of  the  waste  acid  that  is  not  revivified  can  generally  be  utilized 
to  some  extent  for  the  manufacture  of  nitric  acid.  The  remainder,  if  any. 
must  be  reconverted  into  the  separate  acid-,  nitric  and  sulphuric.  The 
greater  part  of  the  nitric  acid  can  be-  di-tilled  off  in  a  retort,  and  i-  thus 
obtained  a-  concentrated  acid  again.  Some  weak  nitric  acid  can  be  added 
to  the  charge  in  the  retort  at  the  same  time,  and  so  be  worked  up  again.  It 
i-  not  practicable  to  distil  off  the  last  traces  of  nitric  acid  in  this  way.  and 
consequently  it  is  necessary  to  pass  the  residual  sulphuric  acid  down  the 
denitrating  tower  before  reconcentrating  it  in  a  Kessler  plant.  In  many 
work-  no  attempt  is  made,  however,  to  recover  any  of  the  nitric-  acid  in  con- 
centrated form,  and  all  the  waste  acid  to  be  treated  is  passed  at  once  down 
the  denitrating  tower. 

The  waste  acid  from  the  manufacture  of  nitro-glycerine  always  contains 
some  of  this  Bubstance,  or  mono-  or  di-nitro-glyoerine  in  solution.  When 
tin-  waste  acid  is  heated  this  decomposes  with  the  production  of  considerable 
quantities  of  the  lower  oxides  of  nitrogen.  Tor  this  reason  it  is  difficult 
to  obtain  strong  nitric  acid  of  good  quality  directly  from  it.  It  cannot  be 
revivified  cither,  because  the  organic  matter  in  solution  would  be  liable  to 
decompose   when  the  acid   was   heated   by   the  addition  of  strong   sulphuric 


MIXED   ACID  125 

acid.  Moreover,  there  would  be  some  nitro-glycerine  formed,  which  would 
separate  out  in  the  storage  tanks  and  other  places  and  give  rise  to  accidents. 
The  whole  of  the  nitro-glycerine  waste  acid  has  therefore  to  be  denitrated. 

The  waste  acid  from  the  manufacture  of  nitro-aromatic  compounds  can  Nitro-com- 
often  be  utilized  after  revivification  for  the  nitration  of  a  further  charge.  p0",nd  waste 
In  some  cases  it  is  used  in  a  lower  stage  of  the  nitration.      .Some  further 
information  about  this  is  given  in  Chapters  XIX  and  XX. 

The  denization  of  the  waste  acid  is  carried  out  in  a  tower,  down  which  Denization 
the  acid  runs  :    at  the  bottom  steam  or  hot  air,  or  both,  are  blown  in.     The  plant' 
nitric  and  nitrous  acids  are  thus  removed  from  the  liquid  and  pass  up  the 
tower  as  vapour  and  gas  respectively.     These  towers  are  frequently  made 
of  vol  vie  stone  cemented  together  with  water-glass    and    asbestos    powder, 
and  filled  with  pieces  of  broken  stone- ware  and  glass.     They  are  often  as 
much  as  10  feet  high  and  18  inches  in  diameter  to  deal  with  some   1500   lb. 
of  acid  per  hour,  but  a  much  smaller  plant  would  deal  with  this  quantity 
equally  effectively.     A  short  denitration  tower  has  the  advantage  that  the' 
gases  are  not  heated  so  long,  and  consequently  there  is  less  loss  of  nitric  acid 
by  formation   of  nitrogen  and  nitrous   oxide.     It  is,   of  course,   important 
that  the  liquid  and  gases  be  well  distributed  and  brought  into  intimate  and 
repeated  contact  with  one  another.     In  England  it  is  usual  to  denitrate  with 
steam  only  :    it  is  thus  easy  to  drive  the  nitric  acid  completely  out  of  the 
weak  sulphuric.     This  is  facilitated  by  the  dilution  which  the  sulphuric  acid 
undergoes  from  the  condensation  of  the  steam,  for  weak  sulphuric  acid  does 
not  retain  nitric  and  nitrous  acids  so  obstinately  as  when  it  is  concentrated. 
In  Germany  the  steam  is  often  made  to  inject  heated  air  with  it  into  the 
base   of  the   denitrating   tower  :  *    a   somewhat   stronger    sulphuric    acid  is 
thus  obtained,  containing  78  instead  of  70  per  cent.,  but  as  it  has  to  be 
reconcentrated  in  any  case,  this  is  not  a  matter  of  great  practical  importance. 
Moreover  the  stronger  acid  retains  nitrous  acid  very  obstinately  in  the  form 
of  nitrososulphuric  acid,  HSN05.     In  Evers's  patent  plant,  steam  and  hot 
air  are  injected  at  four  different  places  in  the  tower  (fee  Fig.  25)  ;    the  heat 
of  the  sulphuric  acid  flowing  from  the  base  of  the  tower  is  utilized  to  heat 
the  air.     Superheated  steam  is  also  used  sometimes.2 

The  gases  escaping  from  the  top  of  the  tower  consist  of  nitric  acid,  water  Recovery  of 
vapour  and  oxides  of  nitrogen,   and  if  air  has  been  injected   nitrogen  and  mtnc  acid* 
oxygen,  also  some  carbon  monoxide  and  dioxide  from  the  decomposition  of 
the  organic  matter  in  the  waste  acid.     In  order  to  condense  the  nitric  acid 
it  is  necessary  to  cool  the  gases.     Formerly  this  was  done  by  air  cooling,  the 
gases  being  led  through  a  number  of  earthenware  jars  or  "  tourils  "  ;  in  the 

1  See  Rudeloff,  S.S.,   1907,  p.   247. 

2  See  H.  Lemaitre,  M onUeur  scientifique  QuesneviUe,  1913,   j>p.  217-231  :   S.S,,   1914, 
pp.   :30  and   48. 


126  EXPLOSIVES 

Evers  plant  (Fig.  25)  air-cooled  earthenware  pipes  are  used,  the  surface  being 
increased  by  subdividing  the  pipes  at  interval-  into  a  large  number  of  small 
pipes.  The  best  method  of  cooling  is,  however,  to  take  the  gases  through 
pipe-  immersed  in  a  trough  of  water  bo  arranged  that  the  condensate  can 

tl'.u   away  into  receivers.     Before  cooling  the  gases  they  should  be  mixed 
with   air.   if  it    has  not   already   been   injected   in   sufficient   quantity.      This 
oxidizes  any  nitric  oxide  to  peroxide,   and  if  water  be  present  it  com 
part   of  it  into  nitric  acid. 

From  the  condenser  the  _  bs  to  absorption  towers,  where  they  meet 

a  stream  of  water  and  the  remaining  nitric  oxide  is  converted  into  nitric  acid. 
It  i-  essentia]  that  an  excess  of  oxygen  be  present  in  the  tra>  to  effect  the 
(•••nvei -imi  in  accordance  with  the  equation  :  4NOa  ■+-  O*  +  2HJ)  =  -±HX03. 
Whether  the  condensation  is  complete  can  be  seen  by  the  appearance  of  the 
gas  escaping  from  the  last  tower  :  it  should  oot  be  red  nor  give  much  fume 
with  the  air.  Whether  there  is  an  excess  of  oxygen  in  the  gases  can  be 
ascertained  by  analysis  :  a  sample  of  the  gas  is  first  shaken  with  distilled 
water  until  there  is  no  further  absorption,  then  with  caustic  alkali  to  absorb 
any  carbon  dioxide,  and  finally  with  alkaline  pyrogallol.  when  there  should 
be  a   distinct   further  diminution  of  volume. 

The  absorption  tower-  are  of  Btone-ware  and  should  be  filled  with  some 
acid-resisting  material  so  a-  thoroughly  to  distribute  both  the  ascending  .  - 
and  the  descending  liquid,  and  bring  them  repeatedly  into  intimate  contact 
with  one  another  and  cause  them  to  mix.  The  Lunge  plate-  do  all  this  very 
efficiently  if  they  are  in  perfect  working  order,  but  if  the  plates  are  not  quite 
true,  or  if  they  get  .-lightly  out  of  the  level,  the  liquid  all  run-  down  one  Bide 
of  the  tower  and  the  gas  ascends  on  the  other,  and  very  little  absorption  takes 
place.  If  one  lays  one's  hand  on  a  Lunge  tower  that  is  working,  one  will 
often  find  that  at  one  part  of  the  circumference  the  shell  is  quite  hot  whilst 
the  rest  i-  cold,  Bhowing  that  action  i-  only  taking  place  in  a  portion  of  the 
tower.  Guttmann's  hollow  -tone-ware  balls  give  a  very  good  result  and 
have  the  merit  that  no  special  care  i-  required  in  filling  them  into  the  tower. 
There  are  many  other  form-  of  -tone-ware  filling  for  towers  procurable.  In 
order  to  effect  complete  absorption  of  the  oxides  of  nitrogen  two  or  three 
tower-  are  necessary.  A  -low  stream  of  water  i-  run  into  tin-  la-t  one  and 
distributed  uniformly  over  the  cross-section  of  the  tower.  A  weak  nitric- 
acid  runs  out  at  the  bottom  of  tin-  tower  ami  i-  raised  from  there  by  means 
of  a  continuously  acting  appliance  to  the  top  of  the  next  one.  A-  weak 
nitric  acid  attack-  all  the  common  metal-,  glass  and  stone-ware  are  the  only 
material-  that  can  be  u-ed  for  the  construction  of  the  pipes  and  vessels.  For 
raising  the  liquid  to  the  tops  of  the  towers  -mall  Ke-tner  automatic  eggs 
made  <»f  Btone-ware  can  lie  u-ed.  but  as  the  quantity  is  very  -mall  it  i-  better 
to  use  a  -mall  appliance,  which  cau-e-  the  acid  to  raise  it-elf  and  works  on 


128  EXPLOSIVES 

the  well-known  principle  of  making  the  ascending  column  of  liquid  lighter 
than  a  descending  one  by  mixing  it  with  ah*.1  From  the  base  of  a  tower  a 
glass  tube  descends  a  distance  equal  to  about  half  the  height  of  the  tower. 
It  tlu-n  turn-  through  180  .  and  a  small  distance  beyond  the  bend  compressed 
air  i-  injected  in  through  a  number  of  small  holes.  When  once  the  rate  of 
admission  <»f  the  air  has  been  adjusted  the  appliance  works  continuously  and 
requires  very  little  attention.  The  mixture  of  acid  and  air  should  be  delivered 
into  the  top  of  the  tower  below  the  cover,  so  that  the  air  cannot  carry  away 
part  of  the  acid  fumes.  This  air  also  serve-  a  useful  purpose. in  that  it  renews 
the  Bupply  of  oxygen,  which  has  been  partially  exhausted  by  the  oxidation 
of  the  nitrous  gases.  The  greater  pari  of  tie'  absorption  of  the  gases  takes 
place  in  the  middle  tower  or  towers  :  in  the  first  tower  the  acid  is 
strengthened  up  slightly  to  near  the  limit  theoretically  possible,  namely. 
68  per  cent.  UNO,.  In  the  last  tower  the  last  traces  of  fume  are  absorbed. 
The  acid  from  the  condenser  generally  has  a  specific  gravity  of  1-41  to 
1-42  and  contains  67  to  69  per  cent.  UNO,  :  that  from  the  towers  is  somewhat 
weaker. 


MANIPULATION   OF   ACID 

S  •  far  a-  possible  acids  of  all  sorts  should  he  conveyed  about  the  work- 
in  pipes  and  not  in  tanks,  carboy-  or  bottles.  In  a  factory  which  make- 
it-  own  acid-  and  reconcentrates  them  there  is  no  reason  why  these  vessels 
should  ever  be  u-ed  at  all  except  in  case  of  emergency.  Wherever  it  is  feasible 
the  acid-  should  run  from  one  place  to  another  by  gravity,  but  of  course 
this  i-  only  possible  to  a  limited  extent,  and  when  the  acid  has  come  down 
to  the  ground  level  it  is  necessary  to  raise  it  again. 

For  strong  sulphuric,  mixed  ami  waste  acid-,  tanks,  pipes  and  other 
appliances  of  either  iron  or  lead  can  be  used  and  last  for  a  very  long  time. 
Iron  i-  cheaper  in  first  cost,  but  lead  can  be  sold  for  a  good  price  after  it  has 
been  u-ed  :  iron  ha-  the  further  advantage  that  it  can  be  fitted  up  by  any 
skilled  workman,  whereas  lead  can  only  be  joined  by  a  lead  burner.  Special 
sorts  of  iron  are  made,  such  as  tantiron.  duriron  and  eorrosiron.  which  resist 
acids  particularly  well,  so  that  they  can  even  be  used  for  concentrating 
sulphuric  acid  and  condensing  nitric  acid.  These  metals  are  very  rich  in 
silicon  and  are  consequently  more  brittle  than  ordinary  cast  iron.  Ordinary 
L'-hi'-h  wrought-iron  steam  piping  fulfils  most  of  the  purposes  of  an  acid  factory. 
Storage  tanks  can  also  be  made  of  iron  or  steel  boiler  -plates.  Strong  nitric 
acid  ha-  little  action  upon  iron,  but  the  dilute  acid  dissolves  it  rapidly.  The 
vapour  that  rises  from  the  surface  of  the  acid  is  much  more  dilute  than  the 

1  .So    /'.  <t  >'..  woL  vii..    L894,  j».  91. 


w/////////y/////////y///////^ 


VOL.    I. 


Fig.  26.     Keetner  Automatic  Elevator  or  "  Egg  " 
129 


130 


EXPLOSIVES 


acid  itself,  and  where  this  condenses  it  is  liable  to  attack  iron  strongly. 
Consequently  it  is  better  to  use  vessels  and  pipes  of  lead  for  this  acid. 
Stone- ware  is  also  used  very  largely  with 
nitric  acid.  Posed  silica  ware,  such  as 
vitreosil,  i>  however  better,  especially  where 
hot  acids  are  dealt  with,  as  its  coefficient  of 
expansion  is  very  small  and  consequently 
there  is  very  little  tendency  to  crack.  For 
use  at  high  temperatures  a  proportion  of 
zirconium  or  titanium  oxide  is  added  to 
prevent  devitrification  of  the  silica.  Con- 
densers for  nitric  acid,  basins  of  cascade 
plants  for  the  concentration  of  sulphuric 
acid,  caps  for  Kessler  plants  and  many 
other  articles  are  made  of  this  material. 
Aluminium  is  also  sometimes  used  a-  a 
material  of  construction  for  acid  plant,  but 
in  most  cases  possess- 
no  advantage  over  iron 
or  lead. 
Raising  acid.  Where  acid  i>  running 

in  a  continuous  stream 
one  of  the  best  appliances 
to  use  for  raising  it  is  an 
automatic  egg  such  as 
that  of  Kestner.  the  con- 
struction of  which  is 
shown  in  Fig.  26.  The 
liquid  in  the  feed-tank.  .-1. 
runs  by  gravity  into  the 
body,  B,  of  the  elevator 
or  egg.  A-  soon  a-  the 
body  is  full  the  liquid 
raises  the  float.  }'.  which 
by  means  of  the  rod.  ('. 
close-  the  air  exhaust 
valve  and  opens  another 
valve  which  admits  com- 
pressed air.  The  pressure  Fig.  2"; 
closes  the  valve,  M,  and 

force-    the    liquid    up    the   pipe,  T,  into    a    high-level    tank.      The    air    after 
delivering  the  liquid   exhausts  through  the   same  pipe   causing   the   pressure 


Kestner  Automatic  Elevator  for  Nitric  Acid. 


MIXED  ACID  131 

to  fall  and  the  valves  to  resume  their  former  positions  :  the  cycle  of  opera- 
tions then  repeats  itself  automatically  in  the  same  manner.  These  eggs 
can  be  obtained  made  of  iron,  with  or  without  a  lead  lining,  or  of  earthen- 
ware. Fig.  27  shows  one  type  of  the  appliance  specially  devised  for  nitric 
acid.  It  can  be  fitted  with  a  meter,  which  automatically  registers  the 
quantity  of  liquid  that  has  been  raised.  A  type  of  elevator  is  also  made 
with  a  double  body  so  connected  up  as  to  give  a  continuous  stream  of 
acid.  Acid  can  also  be  raised  by  means  of  a  centrifugal  pump  driven  either 
electrically  or  by  a  belt. 

Where  the  acid  has  to  be  raised  only  occasionally,  a  non-automatic  egg 
can  be  used.  This  is  simply  a  strong  vessel  made  of  one  of  the  materials 
just  mentioned  and  fitted  with  three  pipes,  one  for  the  admission  of  the  liquid, 
one  for  delivery,  and  one  for  air.  The  inlet  and  the  air  pipes  are  provided 
with  valves  which  are  operated  by  the  attendant. 

When  acids  have  to  be  transferred  from  bottles,  carboys  or  drums  to  a 
storage  or  mixing  tank,  they  can  be  tipped  in  through  a  funnel  placed  higher 
than  the  top  of  the  tank  and  connected  with  it  by  a  pipe.  In  the  case  of 
oleum  containing  60  to  70  per  cent,  anhydride  there  is  some  difficulty  in  Oleum, 
consequence  of  the  great  volumes  of  most  objectionable  fumes  that  it  gives 
off,  especially  as  the  acid  has  to  be  warmed  to  keep  it  liquid.  The  production 
of  fumes  can  be  almost  entirely  avoided  by  the  following  device  :  The  drum 
of  acid  is  raised  to  a  platform  above  the  level  of  the  tank  to  which  it  is  to  be 
transferred,  and  a  pipe  is  inserted  through  the  bung-hole,  the  other  end  of 
the  pipe  going  to  the  bottom  of  the  tank.  A  vacuum  is  then  produced  in 
the  tank  by  means  of  a  steam-jet  working  through  an  ejector  :  as  soon  as 
there  is  sufficient  vacuum  the  oleum  starts  to  flow  over,  and  mil  then  siphon 
over  by  itself  without  any  further  assistance  from  the  ejector.  These  ejectors 
can  be  obtained  made  of  special  acid-resisting  alloys,  but  those  made  of  ordinary 
iron  withstand  the  mixture  of  steam  and  acid  fumes  quite  well. 

Oleum  is  kept  and  transported  in  wrought-iron  drums  ;  cast-iron  is  liable 
to  burst  in  consequence  of  the  oxidizing  action  of  the  acid  on  the  carbon. 
Metals  are  attacked  by  60  per  cent,  oleum  considerably  less  than  by  20  per 
cent,  oleum. 


PART    IV 

NITRIC  ESTERS   OF  CARBO 
HYDRATES 


CHAPTER  X 
THEORY  OF  NITRATION  OF  CELLULOSE 

Stages  of  nitration   of   cellulose   :  Highest   attainable    nitration   :   Solubility  : 

Soluble  nitro -cellulose  :   Quantity  of    acid  :  Consumption  of    acid   :  Effect  of 

nitrous  acid  :  Temperature  and   time  of    nitration  :  Nature  of  the  cotton  : 

Nitro-cottons  of  low  nitration  :  Pyroxylin  :  Collodion 

Cellulose  being  a  non-volatile  colloid,  all  the  ordinary  methods  of  determin-  stages  of 
ing  its  molecular  weight  are  inapplicable,  and  it  is  only  possible  to  deduce  it  "JJjjJJJJJ  ° 
from  a  study  of  the  compounds  that  it  forms.  At  first  the  simplest  possible 
formula  was  assumed  for  cellulose,  C6H10O5,  and  gun-cotton  of  high  nitrogen 
percentage  and  low  solubility  in  ether-alcohol  was  supposed  to  be  formed 
by  the  substitution  of  three  N02  groups  for  hydrogen  atoms,  C6H705(N02)3, 
and  was  consequently  called  trinitro-cellulose.  The  less  nitrated  product 
soluble  in  ether-alcohol  was  similarly  supposed  to  be  the  dinitro-cellulose 
C  6H805(NO  2)  2.  Later  workers  obtaining  evidence  of  intermediate  stages 
of  nitration  proposed  to  increase  the  formula  of  cellulose  :  Eder  1  doubled 
it,  Vieille  2  quadrupled  it,  and  Mendeleeff  3  octupled  it,  giving  48  atoms  of 
carbon  to  each  molecule,  and  hydrogen  and  oxygen  in  proportion.  A  nitro- 
cellulose having  the  composition  of  the  above-mentioned  trinitro-compound 
would  contain  14-14  per  cent,  nitrogen.  Quite  as  much  as  this  has  never  Hignest 
been  found  by  the  analysis  of  any  product  that  has  ever  been  obtained,  but  attainable 
various  investigators  by  nitrating  with  mixtures  of  nitric  acid  and  phosphorus 
pentoxide,  or  with  concentrated  sulphuric  and  nitric  acids  and  extracting 
the  product  with  ether-alcohol  have  obtained  percentages  between  13-9  and 
14.4  Lunge  and  Bebie  5  found  that  with  mixtures  of  sulphuric  and  nitric 
acids  the  highest  percentage  of  nitrogen  was  attained,  not  with  anhydrous 
acids,  but  with  mixed  acids  containing  11  or  12  per  cent,  of  water  :  with  a 
mixture  in  which  the  proportions  H2S04 :  HN03 :  H20  were  63-35  :  25-31  : 
11-34  they  produced  a  nitro-cotton  containing  13-92  per  cent,  N,  but  this 

1  Ber.,   13,  p.   1(39.  2  P.  et  S.,  p.  2;    C.R.,  96,  p.    132. 

3  Moniteur  scientifique,   1897,  p.  510. 

4  See  Eder,  Vieille,  loe.  cit.  ;    Hoitsema,  Any.,  1898,  p.  173  ;    Lunge  and  Weintraub, 
Ang.,    1899,  p.    144.  5  Aug.,   1901,  p.   514. 

135 


136  KXPL0SIY1> 

was  not  stable.1  After  keeping  in  the  wei  Btate  it  was  re-analysed  and  found 
to  contain  then  only  13">  per  cent.  X.  and  other  nitro-eottons  nitrated  almost 
as  highly  were  found  to  decompose  rapidly  until  the  same  composition  was 
reached,  even  though  the  matt-rial  was  kept  tinder  water.  This  corresponds 
very  closely  with  the  formula  C24H.<>  \<  i,)n.  endeka-nitro-cellulose. 
Hence  the  authors  conclude  that  the  molecule  with  24  atoms  of  carbon  fits 
the  facta  sufficiently  well,  but  point  out  that  this  is  only  the  lower  limit  of 
the  possible  size  of  the  cellulose  molecule,  as  to  the  real  magnitude  of  which 
there  is  little  or  no  evidence. 

Hake  and  Bell,  by  nitrating  niter-paper  with  a  mixture  of  concentrated 
sulphuric  and  nitric  acids  in  the  proportion  3  :  1  for  several  days,  obtained 
a  percentage  of  nitrogen  as  high  as  13-96,  but  their  product  was  washed  only 
with  cold  water,  whereas  Lunge  and  Bebie  washed  theirs  for  several  days 
with  hot   water.2 

With  the  possible  exception  of  this  endeka-nitro-cellulose  no  definite 
stages  of  nitration  can  be  recognized  :  nitro-celluloses  with  every  percentage 
of  nitrogen  from  7  to  13-5  and  more  can  be  produced,  and  those  of  the  same 
degree  of  nitration  may  be  soluble  to  very  different  extents  in  ether-alcohol. 
To  characterize  a  nitro-cotton  it  is  better  to  specify  the  percentage  of  nitrogen 
and  the  solubility  rather  than  to  state  the  number  of  X02  groups  that  it 
is  supposed  to  contain  in  each  molecule.  The  following  Table  shows  the 
percentages  of  nitrogen  and  the  volumes  of  gas  evolved  in  the  nitrometer 
by  the  different  nitro-celluloses  of  the  C24  series.  The  figures  have  been 
calculated  using  the  latest  atomic  weight-. 


Formula 

C.c.  NO  per  1  g. 

Per  rout.  X 

Dodeka  -nit  ro  -cellulose 

(^H^O^XO,),, 

225-6 

1414 

Endeka-nitro-ct'llul"-.- 

Cf4H»0lt(NOt)11 

2150 

13-48 

Deka -nit  ro -eel  lull  Me 

('24H3o020(X02)10 

203-5 

12-76 

Ennea-nitro-cellnli 

c24H31O20(XO2)9 

190-9 

11  H7 

Okto-nitro-celluloee 

<'24H32O20U\(>.  . 

177-:: 

11-12 

Hepto-nitro-cellulose   . 

'  lAgO^NO, 

lt.LM 

10-18 

H<-xa-nitii>-c-<-lhil<>se     . 

<  ..H^O^XO^, 

146-0 

9-15 

Penta  -nit  ro  -cellulose    . 

1  ..HjsO^XO^, 

L27-9 

Tetra-nitro-cellulose     . 

CtJ*t&m(SOt), 

107-9 

6-77 

Nitro-celluloee  containing  up  to  12-7   per  cent.  X  can  be  obtained   by 

1  It  i-  of  interest  to  note  that  the  velocity  of  nitration  of  aromatic  compounds  dis- 
solved in  sulphuric  acid  La  at  ;«  maximum  when  the  molecular  proportion  of  sulphuric 
arid  to  water  i-  1  0-7  OT  about  114  per  cent.  H..O  l>v  weight.  (Martinsen.  Z.  f.  phyrik. 
<  ..    1904,    50,   p.   :*85.) 

1  8»         See.  Chan.  ItuL,   1909,  p.  4.V7. 


Theory  of  nitration  of  cellulose  137 

nitrating  with  nitric  acid  alone,  but  only  with  difficulty,  and  the  structure  of 
the  fibres  is  much  damaged.  In  practice  mixtures  of  sulphuric  and  nitric  acid 
are  always  used.  Various  investigators  have  made  numerous  experiments 
to  ascertain  the  effect  upon  the  product  of  altering  the  composition  of  the 
acid  mixture.  The  results  published  by  Bruley,1  Lunge  and  Bebie  (loc.  cit.), 
and  Saposhnikoff  have  been  collected  together  by  the  last-named  and  plotted 
on  triangular  co-ordinates,  the  best  method  of  representing  the  composition 
of  ternary  mixtures.'2  The  numbers  on  the  central  line  running  from  each 
corner  (Fig.  28)  represent  not  the  percentages  by  weight  but  the  molecular 
percentages,  obtained  by  dividing  the  percentage  by  weight  of  each  of  the 
three  constituents  by  its  molecular  weight,  adding  together  the  figures  thus 
obtained  and  working  out  the  percentages  afresh.  On  the  same  figure 
Saposhnikoff  has  also  given  the  vapour  tensions,  which  have  already  been 
presented  in  another  form  in  Fig.  24.  It  will  be  seen  that  for  equal  percentages 
of  nitric  acid  the  vapour  tension  is  a  maximum  on  the  fine  joining  the  points 
marked  HN03  and  H20,  H2S04,  or  slightly  to  the  left  of  it,  This  shows 
that  when  water  is  present  in  excess  it  combines  with  the  nitric  acid  to  form 
a  less  volatile  compound,  but  on  the  addition  of  sulphuric  acid  this  removes 
the  water  from  the  combination  and  combines  with  it  instead.  There  is  no 
evidence  of  any  combination  of  the  sulphuric  with  the  nitric  acid.  The  three 
curves,  I,  II,  and  III,  indicate  the  degree  of  nitration  of  the  cotton  :  the  space 
inside  curve  I  is  the  region  of  the  endeka-nitro-cottons  (about  13-5  per  cent.  N), 
that  between  I  and  II  the  region  of  the  deka-nitro-cottons  (12-8  per  cent.  N), 
and  between  II  and  III  that  of  the  lower  nitrates  with  nine  to  six  nitro  groups 
(12  to  9  per  cent.  N)  ,  beyond  curve  III  nitration  is  incomplete.  It  will  be 
seen  that  the  nitration  curves  follow  a  course  similar  to  that  of  the  vapour 
pressure  curves  :  it  seems  that  the  compound  HNOa,H20  has  little  action 
on  cellulose  and  that  the  presence  of  sulphuric  acid  is  required  to  set  free  the 
nitric  acid  from  this  combination  before  it  can  act. 

The  percentage  of  nitrogen  in  a  nitro-cellulose  is  the  principal  factor  in  Solubilities, 
determining  the  amount  of  energy  that  will  become  available  when  it  explodes  ; 
hence  the  importance  of  attaining  a  high  degree  of  nitration.  A  very  large 
proportion  of  the  nitro-cellulose  manufactured  is  afterwards  converted  into 
a  dense  colloid  by  treatment  with  a  solvent,  whereby  the  original  fibrous 
structure  of  the  cellulose  is  destroyed.  The  properties  of  this  colloid  and 
the  nature  of  the  solvent  to  be  employed  depend  upon  the  solubility  of  the 
nitro-cellulose  :  hence  the  importance  of  determining  this  property.  The 
solvent  used  for  the  determination  is  almost  invariably  a  mixture  of  two 
parts  of  ether  and  one  part  of  alcohol.  The  series  of  experiments  by  Bruley 
and   Lunge   and   Bebie   included   determinations   of    the    solubilities   of   the 

1  P.  et  S.t  vol.  viii.,    1895-1890. 

2  Report  of  7th  Inter.  Congress  Applied  Chem..  Section  1IIB.,  p.  4 1  ;    S.S.,  1909.  p.  442. 


138 


EXPLOSIVES 


oitro-cottons.     Their  results  are  shown  in  fig.  29  together  with  Sapoehnik 
nitration  curvee  :   inside  the  inner  U-shaped  dotted  curve  is  the  region  of  the 

HNO, 


ii 

-*i^-\ 

,5 

s 

35  mm*  /      \ 
20  nnn.  /  % 

i  - 

v« 

25  mm./  \lH      /ft 
/      J  \i       /       i\ 

/  *     /    \>     /         \ 
15  mm./      s    h    \    1 

A// 

o                 A/          > 

y.30  tarn. 

10  mmy        *    \A     \  /  v 

i 

\        '/  \  ' 

\   //       /\ 

V/     '    \  / 

^    /Y     •      V 

\25  mm. 

/  ■  ^4/1  \   h 

5  mm.  /          i  \/x  1     yOy. 

x. 

-'A''  / 

^^U3,H2S0¥ 

A     VX'I    vN 

/      \  / «     K  /  / N  t 

/          "x  /  •      ^\//    m 

VL5  mm. 

VA 

/  \  /»  V  An  /\ 

\ 

\^f    \    ~/-\10 

"T\      -  -<; "ii  \ 

mm. 


-■ 


;n 


V-\-  -  \- 


s 


H2O,H,S0, 

Fig.  28.     Degree  of  Nitration  of  Nibro-cotton  a~  a  Function  of  tIh-  Molecular 
mpoaition  of  Mixed  Acid  and  the  Vapour  Tension  <>f  tin-  Nitric  Acid 

collodion  cottons  completely  or  almost  completely  soluble  in  ether-alcohol. 
The  nitro-cottons  between  the  two  curves  have  an  intermediate  degree  of 
solubility,  1<>  to  !♦<•  per  cent.  ;  (hose  outside  the  outer  one  are  almost  insoluble. 


H2S0< 


THEORY   OF   NITRATION   OF  CELLULOSE  139 

It  will  be  seen  that  the  molecular  percentage  of  water  in  the  mixed  acid  is 
the  principal  factor  in  determining  the  solubility.     This  diagram  will  be  of 

HNO, 


-to. 


HN03  ,HX 


O3  ,HxSO¥ 


HzO,HzSCV 

Fig.  29.      Degree  of  Nitration  and  Solubility  of  Nitro-cotton  as  a   Function  of 
the  Composition  of  the  Acid 

assistance  in  determining  what  composition  of  acid  is  required  to  produce 
a  nitro-cotton  with  any  specified  degree  of  nitration  and  solubility,  but  it 
must  be  remembered  that  it  is  based  on  laboratory  experiments,  which  were 


140 


EXPLOSIVES 


Soluble  nitro- 
cellulose. 


carried  out  under  very  different   conditions  from  those  that   prevail  in  the 

work-. 

The  cotton  used  for  these  experiments  was  generally  cotton-wool,  which 
i-  different  in  many  respects  to  the  cotton  waste  mostly  used  on  the  large 
Bcale  :  it  i-  of  much  inure  open  texture,  each  fibre  being  separated  from  the 
<>thei>..  bo  that  the  acid  can  -oak  iii  very  readily,  thus  facilitating  the  nitration. 
But  as  a  result  the  material  i-  very  bulky,  and  for  this  reason  inconvenient 
to  use  on  a  manufacturing  scale,  as  it  requires  a  very  large  proportion  of  mixed 
acid.  Cotton-wool  lias  often  been  subjected  to  a  very  drastic  bleaching  and 
Bcouring  process,  whereby  the  properties  of  the  cellulose  and  of  the  resulting 
nitro-cellulose  are  injuriously  affected.1 

With  acids  containing  a  very  large  proportion  of  water  or  sulphuric  acid 
nitration  proceed-  very  slowly  and  is  never  complete.  By  raising  the 
temperature  of  nitration  this  can  be  overcome  to  some  extent,  but  then  other 
reaction-  also  take  place  :  oxycellulose  and  nitro-oxycellulose  are  formed. 
and  a  considerable  proportion  of  the  cellulose  is  broken  down  altogether  and 
passes  into  solution.  Thus  Lunge  and  Bebie  obtained  the  result-  Bhown 
below  with  an  acid  of  the  composition  : 


HXO, 


H  ><>, 


H,0 


Per  cent .  by  weight . 
Molecular  per  cent.  . 


4215 
31-7 


38-95 

18-8 


18-90 
49-5 


Time  of  nitration 

4   Bours 
24 

4 

4 

!   Bout 

Temperature 

Per  cent.  N 

Solubility  in  ether- 
alcohol 

Yield  ]>■•! 

IT 

IT 

40 

60° 

60 

11-50 

1  1  -58 
Ll-49 
l'i-sl 
Ll-46 

99-8 

99-0 

Il'.l-S 

!''.iT 

1  .v. 

156 

148 

52 

14T 

The    nitration    was    practically    complete    in    four    hours    at    the    ordinary 
temperature  ;   there  was  only  a  slight  increase  in  the  nitration.  Bolubility  and 

yield,    when    the   time   was   extended    to   twenty-four   hours.      Increase   of   the 

temperature  to  -M»    diminished  the  yield  Bomewhat,  Bhowing  that  the  cellulose 

molecule  itself  was  being  attacked.     At    60     in  four  hour-  this  action   was 
90  -trong  that  the  fibre-  were  entirely  destroyed  and  the  oitro-cellulose  could 


1  Set    Kilmer,  •/.  8oc.  Chem.   I  mi..   1904,  p.  96' 


THEORY   OF  NITRATION   OF   CELLULOSE  141 

only  be  recovered  by  pouring  the  acid  mixture  into  water.  When  the  time 
was  cut  down  to  a  quarter  of  an  hour  this  destruction  of  the  fibre  was  much 
reduced.  Lunge  and  Bebie  found  that  with  increase  in  the  proportion  of 
water  there  was  an  increase  in  the  effect  on  the  structure  of  the  fibre.  Up 
to  15  per  cent,  of  water  by  weight  in  the  acid  mixture  the  structure  appeared 
to  be  unaltered;  but  from  18  per  cent,  upwards  the  fibres  were  somewhat 
drawn  together  and  the  characteristic  twisting  of  the  cotton  fibre  disappeared. 
With  a  further  increase  in  the  percentage  of  water  the  structure  was  destroyed 
almost  completely,  the  lumen  was  torn  open,  and  the  fibres  disintegrated  into 
small  particles  which  were  felted  together  forming  little  lumps.  With  23  to 
25  per  cent,  of  water  this  destructive  action  attained  a  maximum  ;  with  still 
more  dilute  acids  the  fibres  remained  intact  again,  but  on  prolonged  action 
I  hey  were  broken  down  into  smaller  portions.  By  nitrating  cotton  with  a 
mixture  of  H2S04  35-46  per  cent.,  HNO:!  35-45  per  cent,,  H,0  18-20  per 
cent,  in  the  proportion  of  30  of  acid  to  1  of  cotton  at  a  temperature  of  40-50°, 
Claessen  obtains  a  nitro-cotton  entirely  soluble  in  alcohol  (96  per  cent,  by 
vol.)  suitable  for  the  manufacture  of  celluloid.  (Germ.  Pat  163  688  of 
1904.) 

Mendeleeff  and  other  Russian  investigators  have  adopted  a  formula  of  the 
following  form  to  express  the  effect  of  nitrating  with  acids  of  any  particular 
composition  :   if  the  composition  be  written  2HNO,  +  r/H„S04  +  cH,0,  then 
the  "  characteristic  "  is  m,  which  is  equal  to  (1  +  a  —  c).     Acid  mixtures 
with  m  >  O   were  supposed  to  give   products   of   high   nitration   and  low 
solubility,  those  with  m  <  0  soluble  ones.     Those  in  which  the  value  of  m 
exceeded  —  1  by  only  a  little  give  soluble  nitro-cottons  with  a  maximum  of 
nitrogen.     If  m  lies  between  —  0-3  and  +  0-3  the  solubilitv  is  uncertain.     If 
Fig.  29  be  examined  with  reference  to  this  formula,  it  will  be  seen  that  acids 
with  equal  values  of  m  lie  on  a  series  of  straight  lines  all  passing  through  the 
point  marked  H20,H2S04  in  the  centre  of  the  base  line.     If  m  =  —  1  the 
locus  of  the  points  is  the  line  running  from  the  centre  of  the  base  line  to  the 
point  HNO„H20.     These  acids  contain  the  same  number  of  molecules  of 
water  as  of  sulphuric  and  nitric  acids  together.     It  will  be  seen  that  this  is 
indeed  the  locus  of  maximum  solubility,  but  that  the  degree  of  nitration  may 
vary  considerably  on  this  line.     Apparently  in  order  to  get  a  product  perfectly 
soluble  in  ether-alcohol  it  is  necessary  to  have  enough  water  not  only  to  convert 
all  the  sulphuric  acid  into  H4S05,  but  also  all  the  nitric  acid  into  H,N04 
For  m  =  +  1  the  locus  of  the  points  lies  on  the  straight  line  going  vertically 
upwards  from  the  centre  of  the  base  to  the  apex. 

Nitration  is  affected  to  some  extent  by  the  proportions  of  acid  to  cotton   Quantity  of 
because  during  nitration  nitric  acid  is  used  up  and  water  is  formed    so  that  add' 
the  composition  no  longer  remains  the  same.     If  the  proportion  of  acid  to 
cotton  be  very  great  the  composition  only  alters  slightly,   of  course.     In 


142 


EXPLOSIVES 


Consumption 
of  acid. 


Effect  of 
nitrons  acid. 


the  experiments  on  which  Figs.  28  and  29  were  based  the  proportions  were 
generally  50  or  100  :  1.  and  the  consequent  alteration  in  position  on  the 
diagrams  would  only  correspond  to  0-5  to  1-5  molecular  per  cent.  As  a 
molecule  of  water  is  formed  for  every  molecule  of  nitric  acid  used  up.  the 
molecular  percentage  of  tin-  Bulphuric  acid  remains  unaltered,  and  the  point 
representing  tin-  molecular  composition  descends  at  an  angle  of  60c  parallel 
to  the  lines  marking  the  percentage  of  sulphuric  acid. 

T<i  produce  a  nitro-cellulose  with  12*96  per  cent.  X.  exactly  one  part  by 
weight  of  nitric  acid  is  used  up  for  each  part  of  cellulose,  and  1-71  parts  of  the 
nitro-cellulose  should  theoretically  be  obtained.  In  practice  the  yield  is  as 
a  rule  very  nearly  equal  to  the  theoretical.  More  generally  the  connexion 
between  percentage  of  nitrogen  and  consumption  of  acid  is  given  by  the 
equations  : 

1400a; 
V  ~  63  +  45* 
63*/ 


x  = 


1400  —  45?/ 
1400 


280 


1400  —  45y       280  —  9?/ 

where  x  is  the  nitric  acid  used  up  in  the  nitration  of  one  part  of  cellulose,  and 
y  the  percentage  of  nitrogen  in  the  nitro-cellulose  formed,  and  z  is  the  maximum 
theoretical  yield  from  100  parts  of  cotton.  These  equations  apply  equally 
well  to  all  nitration  processes,  whether  of  hydrocarbons  such  as  toluene,  or 
alcohols  such  as  glycerine. 

Lunge  with  his  co-workers,  WVintraub  and  Bebie,  investigated  the  effect 
of  using  nitric  acid  containing  a  considerable  proportion  of  nitrous  acid. 
They  found  that  nitric  acid  containing  as  much  as  6  per  cent.  HX02  gave 
as  good  yields,  as  high  nitrogens  and  as  low  solubilities  as  acid  free  from  this 
impurity.  Even  when  the  proportion  of  nitrous  acid  was  higher  than  this, 
the  effect  was  only  slight.  Lunge  and  Bebie  also  examined  the  stability  of 
tin  products  by  determining  the  explosion  points  and  the  Abel  heat  tests. 
They  came  to  the  conclusion  that  the  nitro-cotton  made  with  acids  containing 
nitrous  acid  is  as  stable  as  that  made  with  acids  free  from  it,  but  their  results 
hardly  bear  this  out.  The  tests  were  in  all  cases  rather  unsatisfactory,  showing 
that  the  products  had  not  been  stabilized  sufficiently  :  the  Abel  tests  were 
no  worse  for  the  "  nitrous  "  products  than  for  the  others,  but  with  the  explosion 
test  the  former  gave  slightly  worse  results  in  every  instance.  The  true  stability 
of  a  nitro-cellulose  is  very  difficult  to  determine  with  certainty,  unless  it  is 
very  bad  indeed  ;  it  can  only  be  ascertained  by  storage  trials  under  various 
conditions  extending  over  months  or  years.     The  evidence,   such  as  it  is, 


THEORY   OF   NITRATION   OF  CELLULOSE 


143 


indicates  that  nitrous  acid  has  a  slightly  bad  effect  on  the  stability.  If  the 
products  had  been  thoroughly  stabilized  perhaps  the  evil  effect  would  have 
been  eliminated. 

Lunge  and  Weintraub  studied  the  influence  of  temperature  and  time  of  Temperature 
nitration  of  cotton  wool  with  a  mixture  of  concentrated  sulphuric  and  nitric  Oration.0 
acids  in  the  proportion  3:1,  and  found  that  with  a  rise  of  temperature  the 
velocity  of  the  action  increases  considerably.1 


Temperature 

Tune 
hours 

Per  cent.  N 

Yield  per  cent. 

Yield 
(oalc.) 

Per  cent,  loss 
of  cellulose 

0° 

i 

10-71 

152-3 

153 

Trace 

0° 

7 

1319 

173-3 

174 

Trace 

10° 

7 

13-37 

175-8 

176 

— 

15° 

7 

13-38 

175-6 

176 

— 

19° 

1 

12-72 

1661 

170 

— 

19° 

7 

13-39 

175-6 

176 

— 

40° 

i 

1307 

172-3 

173 

Trace 

40° 

7 

13  06 

169-6 

173 

1-61 

60° 

1 

13-08 

169-2 

173 

1-95 

60° 

H 

1307 

1621 

173 

5-67 

80° 

i 

1307 

161-2 

173 

6-52 

80° 

i 

Z 

1312 

125-2 

173 

27-4 

80° 

3 

1312 

81-5 

173 

52 -S 

It  will  be  seen  that  at  high  temperatures  the  nitration  proceeds  rapidly 
to  a  maximum  and  then  the  yield  falls  again  ;  the  cellulose  is  first  converted 
quantitatively  into  nitro-cellulose,  and  if  the  action  of  the  acids  be  prolonged 
the  product  dissolves  partly,  and  the  yield  is  consequently  diminished.  The 
part  which  is  not  dissolved  is  also  attacked,  with  the  consequence  that  the 
percentage  of  nitrogen  is  reduced.  In  the  case  of  acids  containing  a 
considerable  proportion  of  water,  this  is  demonstrated  by  the  Table  on  p. 
120,  and  is  confirmed  by  the  following  figures,  which  were  obtained  by  nitrating 
with  concentrated  acids  at  32°  : 


Time  of  nitration 

Per  cent,  nitrogen 

5  ]\Iinutes 

13-27 

15 

13-44 

30 

13-47 

60 

13-50 

120 

13-40 

1  See  also  Lunge,  J.  Amer.   Chem.  Soc,   1901,  23,   p.    527. 


144 


EXPLOSIVES 


Further  Tables  show  the  influence  of  time  with  mixtures  of  concentrated 
nitric  and  sulphuric  acids  in  different  proportions  : 


One-half  hour 

ty-nmr  hours 

Three  day- 

HN 

H;- 

Percent.  X          Yield 

Percent.  X 

Sleld 

Percent   X        Yield 

0 

12-58              162-7 

12-62 

1 63-3 

i 

i  ■• 

— 

12-1               166-0 

—                   — 

13  4.-, 

1 75-7 

13  44             175-8 

—                   — 

— 

— 

13-42              17"   I 

—                   — 

1 

13 

IT- 

13-39            174-8 

—                   — 

•> 

13-2 

1741 

13  :2           17. 

—                   — 

3 

12-72 

166-1 

13-4"            176-4 

13-38            17" 

4 

— 

— 

13-2"            176-1 

—                — 

.) 

B-14             130 

13-10            164 

—                 — 

HNOj 

H,S04 

Three  days 

Fifteer. 

Unnit  rated 

L'nnitratcd 

Percent.  X 

Yield 

cellulose 
per  cent. 

Percent.  X 

Yield          cell'. 

per  cent.* 

1 

12  63 

162-4 

u 

12-74 

169-8            N   ne. 

1 

7 

H»-86 

151-6 

10-46 

— 

—                  — 

1 

7-74 

120-1 

Much. 

— 

—                  — 

• 

_    -  days 

Thirty  days 

1 

8 

l<»-88 

144  -6 

10-7 

11-70 

152-0            4-46 

1 

10 

65-0 

411 

— - 

These  results  indicate  that  when  the  proportion  of  sulphuric  acid  is  increased 
the  velocity  of  action  is  diminished.  This  applies  not  only  to  the  nitration 
procc--  itself,  but  also  t<>  the  subsidiary  actions.  They  show  that  it  is  not 
only  cheaper  but  also  better  to  nitrate  with  a  mixture  containing  a  considerable 
proportion  of  sulphuric  acid,  provided  that  the  acid  can  be  allowed  to  act  on 
the  cotton  for  some  hours,  but  that  if  it  be  desired  to  obtain  a  high  degree  of 

1  25-4  tuinitrated  cellulose. 

2  The  *"  unnit  rated  cellul  determined  by  treating  the  product  with  sodium 
ethylatc  solution.  The  authors  u«e  the  term  '"  unaltered  cellulose.  *  but  the  word  "un- 
nitrated  "  is  preferable,  because  the  cellulose  is  not  unaltered,  although  it  has  not  been 
nitrated  to  an  appreciable  extent. 


THEORY   OF   NITRATION   OF   CELLULOSE 


145 


nitration  in  a  short  time,  as  when  nitrating  in  centrifugals,  for  instance,  the 
proportion  of  nitric  acid  must  not  be  too  small. 

Hake  and  Bell  *  found  that  the  course  of  the  nitration  is  greatly  affected 
by  the  physical  form  of  the  cellulose.  If  this  be  very  dense,  the  acid  cannot 
readily  penetrate  it,  and  the  partly  exhausted  acid  can  only  diffuse  away 
and  be  replaced  very  slowly.  Thus  filter-paper  is  much  slower  in  attaining 
its  maximum  degree  of  nitration  than  cotton- wool,  and  the  thicker  and  denser 
the  paper  is  the  more  is  the  nitration  delayed.  A  larger  proportion  of  sulphuric 
acid  also  combines  with  the  more  dense  material. 


Time  of  nitration 

Cotton  wool 

Swedish  filter 

paper 

Density  1 

"  Heat  test  " 

paper 
Density  1-22 

Thick  filter 

paper 
Density  1-52 

5  minutes 

Per  cent,  n 
11-71 

Per  cent,  n 
10-69 

Per  cent,  n 

Per  cent,  n 
6-1 

15 

1318 

12-84 

11-73 

10-18 

30 

13-41 

13-20 

1317 

11-23 

1  hour 

— 

13-35 

13-38 

12-52 

2  hours 

— 

13-31 

— 

1317 

3       „ 

— 

13-69 

13-84 

13-24 

6 

— 

— 

13-74 

13-43 

1  day 

— 

13-67 

13-86 

13-57 

3  days 

— 

13-93 

13-87 

13-60 

6 

— 

13-96 

13-84 

13-51 

10       „ 

— 

13-82 

13-64 

13-65 

16       „ 

13-90 

13-82 

13-76 

The  acid  used  was  a  mixture  of  concentrated  sulphuric  and  nitric  acids  in 
the  proportion  3:1;  the  products  were  not  stabilized  but  merely  washed  in 
cold  water. 

In  order  to  make  sure  that  the  cotton  wool  which  they  used  for    their  Nature  o! 
experiments  did  not  give  different  results  from  other  sorts  of  cotton,  Lunge 
and  Bebie  carried  out  comparative  nitrations  with  these  different  materials. 
The  acid  used  had  the  following  composition  by  weight  :    H2S04  63-84  per 
cent,,  HN03  16-96  per  cent.,  H20  19-20  per  cent.  ;    the  results  were  : 

Cotton  wool,  chemically  pure 
American  cotton  (middling  fair) 
American  cotton  (Florida) 
Egyptian  cotton,  white  (Abassi) 
Egyptian  cotton,   natural  yellow  quality 

There  is  very  little  difference  between  the  results  with  the  different  cottons  ; 


Per  cent. 

N 

Yield 

.      11-76 

159 

.      11-56 

157 

.      11-67 

153 

.      11-69 

155 

.      11-61 

154 

1  J.  Soc.  Chem.  hid.,   1909,  p.  460. 


VOL.  I. 


10 


Urt 


EXPLOSIVES 


Nitro-cottons 
of  low 
nitration. 


the  difference  in  the  percentage  of  ash  will  account  for  a  large  proportion  of 
what  difference  there  is.  The  cotton  wool  contained  only  005  per  cent.  ash. 
the  other  cottons  about  0-5  per  cent.  The  nitro-cottons  were  all  completely 
soluble  in  ether-alcohol.  The  viscosity  <>f  the  solutions  was  not  determined  ; 
in  this  respect  there  would  no  doubt  have  been  differences. 

The  above  were  all  normal  celluloses  of  good  quality  ;  it  is  when  abnormal 
celluloses  are  nitrated  that  differences  are  found  in  the  yields  and  nitrogen 
percent,!  _ 

Lunge  and  Bebie  (loc.  cit.)  by  nitrating  with  acid  of  the  composition: 
HNO,  3717  per  cent..  H2S04  34-41  per  cent.,  H20  28-42  per  cent,  by  weight 
obtained  a  nitro-cotton  containing  only  6-50  per  cent.  X.  bnt  the  large  amount 
of  basic  dye-stuff  that  it  absorbed  indicated  that  it  was  to  a  large  extent 
nitro-oxycellulose.  With  nitric  acid  alone  of  specific  gravity  1-4  (34-8  mol.  per 
cent.  HX03)  a  product  was  obtained,  of  which  02-9  per  cent,  was  unnitrated 
fibre  as  determined  by  treatment  with  sodium  ethylate  :  allowing  for  this 
the  nitrated  portion  contained  400  per  cent.  N.  It  contained  little  or  no 
oxycellulose  or  nitro-oxycellulose.  When  5  per  cent,  of  sulphuric  acid  was 
added  to  the  nitric,  a  product  was  again  obtained  which  contained  a  large 
proportion  of  oxycellulose  or  nitro-oxycellulose  ;  there  was  about  58  per  cent, 
unnitrated  fibre,  and  the  nitrated  portion  contained  512  per  cent.  X.  Crane 
and  Joyce  x  have  nitrated  cotton  with  acids  containing  little  nitric  acid  and 
much  sulphuric  and  water.     With  an  acid  of  the  composition  : 


HNO  3 
H2S04 
H,0 


By  weight 

Molecular 

90 

6-4 

65-5 

30  0 

25-5 

63-6 

they  obtained  a  product  containing  3-51  per  cent.  X.  It  was  insoluble  in 
acetone,  ether-alcohol,  and  all  the  other  usual  solvent-  for  nitro-cellulose, 
but  soluble  in  strong  acids,  caustic  alkalis,  and  phenol.  Ultimate  analysis 
gave  resultsagreeing  with  the  formula,  CoiHsftOoo,  X02  -f-  2H20.  It  contained 
0  34  percent,  sulphur  and  must  therefore  have  beeD  unstable.  The  composition 
indicates  that  it  was  a  nitro-hydro-cellulose. 
Pyroxylin.  Soluble  nitro-cellulose  or  "pyroxylin"'  is  used  very  largely  outside  the 

explosives  industry  for  the  manufacture  of  varnishes,  photographic  films, 
artificial  silk,  celluloid,  etc.  For  practically  all  these  purposes  ready  solubility 
is  essential,  and  high  viscosity  generally  a  disadvantage.  Therefore  the 
nitration  is  usually  carried  out  at  a  fairly  high  temperature,  but  it  should 
not  be  too  high,  else  the  cohesion  of  the  material  is  injuriously  affected,  and 
this  is  one  of  its  most  important  properties.     According  to  figures  given  by 


1  J,  Soc.  Chem,  ///</..  1910,  i>.  540. 


y  vreighl 

Molecular 

35-4 

26-5 

44-7 

21-5 

19-9 

52-0 

THEORY   OF  NITRATION   OF   CELLULOSE  147 

Worden,1  Hyatt  prepares  the  material  for  high-class  celluloid  by  nitrating 
tissue  paper  with  acid  of  the  composition  : 

HN03  .... 
H2S04  .... 
H20 

The  nitration  is  carried  out  at  a  temperature  of  55°  and  lasts  a  half  to  one 
hour;  there  are  22  lb.  of  acid  per  lb.  paper.  The  product  contains  11-0 
to  11-2  per  cent.  N  and  about  01  per  cent,  ash  ;    the  yield  is  140  per  cent. 

For  commoner  qualities  a  smaller  proportion  of  nitric  acid  is  used. 

Collodion  is  much  used  to  seal  surgical  wounds,  for  application  to  cuts 
and  abrasions,  and  as  a  vehicle  for  the  application  of  drugs  to  the 
skin  when  prolonged  local  action  is  required.  The  pharmacopoeias  of  the 
various  countries  contain  directions  for  the  preparation  of  the  pyroxylin  for 
these  collodions,  but  satisfactory  or  uniform  products  are  not  likely  to 
be  obtained  by  following  them. 

If  the  collodion  cotton  be  of  a  suitable  quality  and  it  be  dissolved  in  Collodioi 
ether-alcohol  together  with  camphor  and  castor-oil,  the  solution  on  drying  will 
leave  a  film,  which  does  not  contract,  In  this  way  incandescent  mantles  are 
coated  with  material  which  enables  them  to  bear  transit.  If  the  film  were 
to  contract  on  drying  the  mantle  would  be  crushed,  and  when  the  collodion 
was  burnt  off  the  mantle  would  fall  to  pieces. 

1  Xitrocellulose  Industry,  p.  113. 


CHAPTER   XI 

CELLULOSE 

bure   of   cellulose  :    Ligno-oellul  I     impound    celluloses   :    Reactions   oi 

cellulose  :  With  sulphuric  acid  :  With  nitric  acid  :  Mercerized  cotton  :  Vis- 
cose :  Cellulose  benzoatee  Acetates  :  Schweitzer's  reagent  :  Hydrate  cellu- 
lose :  Oxy-cellulose  :  Nitro-oxycellulose,  etc.  :  Viscosity  Overbleached 
cotton  :  Nitrated  mercerized  cotton  :  Effect  (if  dilute  alkali  :  Cotton  used  in 
manufacture  :  Wood  cellulose   :  Action  of  bacteria   :  Structure  of  cotton  fibre  : 

Dead  cotton 

(  !omflete  knowledge  of  the  nature  of  the  process  of  nitration  and  the  stability 
of  nitro-cellulose  would  require  a  thorough  acquaintance  with  the  structure 
of  the  cellulose  molecule,  but  in  spite  of  numerous  investigations  there  is  still 
much  that  is  unknown  about  the  chemistry  of  this  substance.  There  are 
few  substances  which  are  more  complex,  or  about  which  it  is  more  difficult 
to  arrive  at  a  definite  conclusion.  This  is  partly  due  to  the  fact  that  cellulose 
comprises  whole  series  of  allied  substances,  which  are  known  by  this  name, 
and  these  are  not  all  distinct  from  one  another,  but  are  liable  to  modifications, 
which  cause  one  variety  to  merge  gradually  into  another.  Cellulose  may  be 
converted  by  reagents  into  product-,  such  as  oxy-cellulose  and  hydro-cellulose, 
which  are  very  similar  to  the  original  substance  in  appearance  and  properties. 
and  only  differ  from- it  very  slightly  in  elementary  composition.  They  are. 
however,  somewhat  more  reactive,  more  liable  to  be  attacked  by  chemical 
reagents.  But  true  cellulose  obtained  from  different  sources  also  shows 
considerable  variations,  although  no  difference  can  be  detected  in  the 
composition.  Even  the  best  cotton  contains  a  proportion  of  material,  which 
can  be  removed  from  it  by  treatment  with  bleaching  powder  and  alkali. 
but  the  separation  can  never  be  carried  to  completion,  because  the  treatment 
also  attacks  the  true  cellulose  although  to  a  le<s  extent.  The  chemical 
behaviour  of  cellulose  cannot  1m-  represented  by  a  formula  containing  24 
or  any  other  number  of  carbon  atoms  :  in  the  nitration  no  definite  stages  or 
well-characterized  nitrate  can  be  distinguished  ;  en  the  contrary  the  nitration 
appears  to  be  a  continuous  process  from   6  up  to   13*6  per  cent.  X.     Cross 

148 


CELLULOSE  149 

and  Bevan  explain  all  this  by  the  theory  that  cellulose  consists  of  a  "  solution 
aggregate,"  that  it  is  a  solid  solution  in  which  substances  of  similar  but  not 
identical  constitution  are  dissolved  in  one  another.  Others  consider  that  the 
union  of  these  different  constituents  is  more  intimate,  and  is  chemical  rather 
than  physical  ;  that  the  cellulose  molecule  consists  of  a  large  number  of 
smaller  groups  combined  together,  and  that  these  groups  may  differ  slightly 
from  one  another  in  configuration  and  even  in  composition.  The  whole 
subject  of  the  chemistry  of  the  colloids,  of  which  class  cellulose  is  such  an 
important  member,  abounds  with  difficulties,  and  it  is  only  recently  that  any 
considerable  effort  has  been  made  to  solve  its  problems. 

Cellulose  is  the  principal  constituent  of  the  framework  or  cellular  tissue 
of  plants  ;  cotton  and  linen  are  almost  pure  cellulose,  but  can  be  further  purified 
by  judicious  treatment,  and  are  then  characterized  by  their  resistance  to 
chemical  action,  as  compared  not  only  with  most  other  organic  materials 
but  also  with  the  allied  cellulosic  substances,  such  as  ligno-cellulose.  pecto- 
cellulose.  and  the  products  obtained  by  the  action  of  reagents  on  cellulose, 
such  as  oxy-cellulose  and  hydro-cellulose.  Cellulose  has  the  empirical 
formula  C6H10O5. 

Of  the  ligno-celluloses  jute  fibre  may  be  taken  as  a  representative.     It  Ligno- 
differs  from  cellulose  by  having  a  higher  ratio  of  carbon  to  oxvgen  : 

Cellulose    . 
Jute  fibre. 

By  treatment  with  chlorine  the  "  non-cellulose  *'  can  be  removed,  but  even 
then  the  residual  cellulose  is  more  reactive  than  normal  cotton  cellulose  and 
contains  a  considerable  proportion  of — O.CH3  groups.  It  is  supposed  that 
cellulose  is  first  formed  in  the  plant,  and  is  afterwards  converted  into  ligno- 
cellulose.  With  the  exception  of  a  few  materials,  such  as  cotton,  hemp,  and 
to  lesser  extent  ramie,  practically  all  the  vegetable  fibres  contain  a  considerable 
proportion  of  the  non-cellulosic  substance  "  pectose."  In  wood  fibre  the 
bonification  has  proceeded  further  than  in  jute.  By  treatment  with  alkaline 
sulphites  a  fairly  resistant  cellulose  can  be  prepared,  and  this  is  now  manu- 
factured on  a  very  large  scale  for  paper-making,  but  the  material  thus  obtained 
is  more  reactive  than  cotton  cellulose.  It  has  been  used  to  a  considerable 
extent  for  the  manufacture  of  sporting  smokeless  powder,  for  which 
purpose  a  high  degree  of  nitration  is  not  so  important  as  a  thorough 
control  of  the  rate  of  burning.  Nitration  experiments  with  jute,  were 
carried  out  by  Muhlhaeuser,1  using  various  mixtures  of  the  concentrated 
acid.  The  fibre  was  purified  firsl  by  boiling  with  1  per  cent,  caustic  soda 
solution. 

1  Dingier' a  Pol.  Jour.,   1892,  283,  p.  88. 


c 

H 

0 

44-37 

6-36 

49-27 

46-47 

61-5-8 

47-9   47-2 

EXPLOSR 

- 

Acids  : 

fibre 

.tion         Yi'-ld  per  cent, 
(hours) 

_ 

per  cent. 

1 
- 
- 

3 

1 
1 
1 
1 

10 

15 
15 

15 

1 
1 
1 

1 

1 

132 
14o 

3                          136 

12-10 

_ 
1 

11-80 
12-04 

11-96 
11-80 

Liono-celluloses    eive  a  number    of    characterise    reactions        Salte      : 

a 

aniline  colour  the  fibre  a  deep  golden-yellow.  Phloro-glucinol.  dissolved  in 
hvdrochlorie  acid,  gives  a  deep  magenta  coloration.     Iodm  aorbed  in 

large  quantity,  colouring  the  fibre  a  deep  brown.  The  fibre  readily  combines 
with  chloriri'  wn  by  the  characteristic  magenta  coloration  developed 

on  the  subsequent  addition  of  sodium  sulphite.     Very  characteristic  is  the 
reaction  with  ferric  ferricyanide.  obtained  by  mixing  equivalent  proportk  : 
potassium  ferricyanide  and  ferric  chloride  :    the  fibre  is  stained  a  deep  blue 
and  takes  up  a  considerable  quantity  of  pigment. 

Matthews  *  classifies  the  compound  celluloses  as  folic     - 

(a)  Pecto-celluloses.  related  to  the  pectin  compounds  of  vegetable  tiae 
represented  among  the  fibres  by  raw  flax  :   resolved  by  hydrolysis  into  pectic 
acid  and  cellul-  - 

•  Ligno-celluloses.  forming  the  main  constituent  of  woody  tissue  and 
represented  among  the  fibres  by  jute  ;  resolved  by  chlorination  into  cellulose 
and  chlorinated  derivatives  of  aromatic  compounds  soluble  in  alkalis. 

(c)  Adipo-celluloses.  forming  the  epidermis  or  cuticular  ti^ue  of  fibres, 
leaves,  etc.  :  resolved  by  oxidation  with  nitric  acid  into  derivatives  >imilar 
to  those  of  the  oxidation  of  fats  and  cellul 

The  fibres  of  cork  and  other  barks  belong  to  the  lasl  as,  but  all  such 
materials  contain  also  large  proportions  of  oils  and  wa  onins,  ligno- 

cellulose   and    nitrogeno         a       "  upo-cellulose    (or   cuto-cellulose) 

contains  a  larger  percentage  of  carbon  than  pure  cellulose  ;    pecto-ceHi 
on  the  other  hand,  has  a  high  proportion  of  oxygen. 

Besides  the  nitro-celluloses  produced  by  the  action  of  mixture^  of  >ulphuric 
and  nitric  acids,  each  of  these  acids  alone  yields  products.  <  oa .<  entrated 
sulphuric  acids  chars  cellulose  and  disc  it.  forming  dextrine  and.  finally, 

glucose  and  other  products  of  a  comparatively  simple  nature.  If  the  acid 
be  diluted  first  with  a  third  of  it>  weight  <>i  water,  the  cellulose  di»olve> 
without  charring  with  the  formation  of  hydro-cellulo-  I  H  ,  < »  aometimes 
called    amyloid,    and    cellulox'->ulphuric    acid   C'iBHsoOi8(SOj)i   (?)  ;    if  the 


1  Allen  __ 


CELLULOSE  151 

action  be  only  allowed  to  proceed  for  a  short  time  and  the  cellulose  be  then 
washed,  the  surface  is  converted  into  a  gelatinous  non-fibrous  film.  In  this 
way  vegetable  parchment  is  made.  Cellulose  combines  very  readily  with 
sulphuric  acid  of  moderate  strength,  but  the  compound  formed  undergoes 
further  changes  very  rapidly.  There  is  reason  to  believe  that  in  the  ordin- 
ary nitration  process  the  cellulose  first  combines  with  the  sulphuric  acid, 
and  that  the  product  then  reacts  with  the  nitric  acid  to  form  nitrocellu- 
lose. 

Hake  and  Bell  found,  however,  that  a  proportion  of  sulphuric  acid  always  Mixed  esi 
remains  combined  with  the  nitro-cellulose,  and  that  the  amount  does  not  ™d  sjjj ' 
diminish  below  a  certain  amount  when  the  time  of  nitration  is  increased,  acids, 
From  this  they  concluded  that  in  normal  nitration  the  nitric  acid  reacts 
directly  with  the  cellulose,  and  that  the  formation  of  the  mixed  esters  is  due 
to  the  absence  of  a  sufficient  amount  of  nitric  acid,  and  the  consequent  inter- 
vention of  some  of  the  sulphuric.1     But  the  evidence  is  inconclusive,  as  the 
compound  first  formed  when  cellulose  is  immersed  in  sulphuric  acid  is  probably 
quite  different  from  the  mixed  esters.     (For  further  discussion  of  these  mixed 
esters  see  p.  188.) 

With  concentrated  nitric  acid  nitro-cellulose  is  obtained.     Vieille  2  found  With  nit 
the  following  percentages  of  nitrogen  in  the  products  yielded  by  acids  of 
different  strengths  : 


icular  per  cent.  HN03 

Per  cent.  N 

80 

12-7 

75 

11-5 

67 

10-2 

57 

9-0  dissolves  in  acid,  reprecipitated  with  water. 

40-42 

7-0  friable  mass. 

With  acid  weaker  than  this  very  little  nitration  takes  place  ;  Saposhnikoff, 
with  an  acid  containing  34-7  molecular  per  cent.  HN03,  obtained  a  product 
containing  only  1-46  per  cent.  N.  Hake  and  Bell,  with  concentrated  nitric 
acid,  obtained  nitro-cellulose  with  as  much  as  13-5  per  cent.  N.3 

Knecht 4  found  that  when  cotton  is  immersed  in  weak  nitric  acid  it  swells  Labile  m 
up  and  forms  a  "  labile  "  nitrate,  from  which  the  nitric  acid  can  be  removed 
again  by  washing  with  water  ;  if  the  cotton  be  in  the  form  of  yarn,  a  contrac- 
tion of  length  takes  place.  To  estimate  the  amount  of  acid  retained  by  the 
cotton  Knecht  squeezed  it  out  and  then  let  it  stand  for  several  days  in  a 
vacuum  desiccator  over  quicklime,  then  immersed  it  in  water  and  titrated 
the  acid  removed.  The  following  are  some  of  the  results  that  he  obtained 
with  acids  of  different  strengths  : 

1  J.  Soc.  Chem.  Ind..   1909,  p.   457.  2  Compt.  Rend.,   1802,   95,  p.    132. 

3  J.  Soc.   Chen>.   Ind.,    1909,  p.  458.  *   Ber.,   1904,  p.  549. 


152 


EXPLOSIVES 


Nitric  acid 

H  N<  »3  retained  by 

cellulose 
Per  cent. 

Contraction  of  yam 
Per  cent. 

Molecular  per  cent. 

Sp.  gr. 

38-4 
34-8 
31-2 
3(M 
23-0 

1-415 

1-400 
1-380 
1-375 
1-325 

35-8 

27-3 
10-8 

7  ."> 
71 

130 

100 

2-6 

in 
in 

If  cellulose  be  heated  with  acids  of  these  strengths  it  is  converted  into  oxv- 
celluloses,  which  contain  a  higher  proportion  of  oxygen  than  cellulose  does. 
and  perhaps  a  lower  proportion  of  hydrogen.1 

As  mentioned  above.  Vieille  found  that  cellulose  was  dissolved  by  acid 
containing  about  57  molecular  per  cent,  nitric  acid.  This  matter  has  been 
more  fully  investigated  by  Jentgen.2  who  found  that  the  most  suitable  strength 
for  the  preparation  of  these  "  xyloidines  '*  at  a  temperature  of  18C  is  58-2  to 
B3-7  molecular  per  cent.  (1-400-1-479  sp.  gr.).  When  solution  is  complete 
it  >hould  be  poured  into  a  large  volume  of  cold  water.  Products  were  thus 
obtained  containing  0-2  and  7-2  per  cent.  X  :  they  were  insoluble  in  ether- 
alcohol,  amy]  acetate  and  acetone  :  ethyl  acetate,  cold  acetic  acid  and  acetic 
anhydride  only  caused  them  to  swell  up,  but  hot  glacial  acetic  acid  dissolved 
them.  With  slightly  stronger  acid  a  somewhat  higher  degree  of  nitration  is 
attained,  and  the  products  are  more  soluble.  A  similar  product  may  be 
obtained  by  dissolving  cellulose  in  sulphuric  acid  and  pouring  into  nitric  arid. 
or  by  dissolving  in  nitric  acid  and  pouring  into  sulphuric.* 

The  formation  of  the  labile  nitrate  of  cellulose  is  very  similar  to  that  of 
the  compound  with  caustic  soda.  If  cotton  be  immersed  in  a  solution  of  this 
alkali,  it  absorbs  some  of  it.  forming  a  combination  in  the  proportion  06Hio05. 
NaOH  ;  the  cotton  swells  up,  and  if  it  be  under  tension  it  acquires  a  lustre 
resembling  that  of  silk.  The  soda  is  removed  again  on  washing  with  water, 
but  the  cotton  is  found  to  have  changed  in  its  properties,  its  tensile  strength 
has  become  greater  and  it  can  be  dyed  more  easily.  This  process  is  known 
as  "  mercerization,"  and  is  much  used  industrially:  for  an  investigation  of 
it  eet  Buhner  and  Pope,  J.8.C.I.,  1904,  p.  4o4.  .Many  other  reagents  besides 
caustic  soda  and  nitric  acid  produce  much  the  same  results,  although  not 
to  the  same  extent  as  soda,  <  .g.  solutions  of  sodium  sulphide,  potassium  mer- 
curic iodide,  barium  mercuric  iodide  and  strong  hydrochloric  acid.     Sulphuric 

1  s>.   alao  E.  Knechl  and  A.   Lipechitz,  •/.  Soc.  Chetn.  //«/..   1!U4.  p.   116, 

-  Ang.%   1912,  p.  1*44. 

3  Haeussermann,  S.S.,  1908,  p.  ::"•">. 


CELLULOSE  153 

and  phosphoric  acids  of  certain  strengths  also  react  in  the  same  way,  but  at 
the  same  time  gradually  dissolve  the  cellulose. 

Cellulose  treated  in  this  way  is  much  more  reactive  than  untreated  cotton,  viscose 
If  to  the  mixture  of  cellulose  and  caustic  soda  solution  carbon  bisulphide  be 
added,  the  material  gradually  swells  up  and  eventually  goes  into  solution, 
forming  sodium  cellulose  xanthate.  This  solution  can  be  made  into  fine 
threads  by  passing  it  through  narrow  jets,  and  if  these  threads  are  treated 
with  alcohol  and  other  reagents,  the  soda  and  carbon  bisulphide  are  removed 
and  a  cellulosic  material  is  regenerated.  This  is  the  basis  of  the  Viscose 
artificial  silk  process. 

If  the  alkali  cellulose  be  treated  with  benzoyl  chloride,  cellulose  benzoates  Cellulose 
are  obtained.     Of  these  two  are  known  :    the  monobenzoate  (C  G)  retains  the  benzoates- 
form  of  the  original  cellulose  ;    the  dibenzoate  is  a  structureless  amorphous 
powder  soluble  in  acetic  acid  and  chloroform. 

Cellulose  acetates  are  formed  by  the  action  of  acetic  acid  and  acetic  anhy-  Acetates, 
dride  on  cellulose  that  has  been  converted  into  hydro-cellulose  by  the  action 
of  strong  acids  or  alkali.  With  unchanged  cellulose  there  is  little  or  no  action. 
In  this  respect  the  formation  of  all  other  cellulose  esters  is  essentially  different 
from  that  of  nitro-cellulose,  for  which  the  most  resistant  cellulose  is  best, 
The  triacetate  (C6)  has  recently  come  into  use  on  a  large  scale  for  making 
films  for  cinematographs,  etc.  It  is  soluble  in  chloroform,  acetone  and 
phenol.  A  tetracetate  and  other  still  higher  derivatives  were  formerly  supposed 
to  exist,  but  the  supposition  was  apparently  founded  on  erroneous  analysis. 

Cellulose  dissolves  in  a  solution  of  copper  hydroxide  in  aqueous  ammonia  Schweitzer' 
known  as  Schweitzer's  reagent,     If  the  ammonia  be  neutralized,  a  cellulosic  reasent- 
substance  is  regenerated.     Pauly's  artificial  silk  process  is  founded  on  this 
solubility.     Cellulose  also  dissolves  in  a  solution  of  zinc  chloride  and  hydro- 
chloric acid,  and  in  various  other  salt  solutions.1 

The  cellulose  regenerated  from  any  of  these  solutions  differs  from  the  Hydrate 
untreated  material  in  being  more  reactive,  and  in  containing  a  larger  propor-  cellulose- 
tion  of  hydrogen  and  oxygen  :  the  elementary  composition  agrees  with  the 
formula  C12H20O10,  H,0,  or  some  mixture  of  this  with  normal  cellulose.  The 
treatment  of  cellulose  with  acids  and  alkalis  yields  very  similar  products, 
and  those  obtained  by  the  hydrolysis  of  nitro-celluloses  and  other  esters  have 
the  same  characteristics.  There  are  considerable  differences,  however,  between 
celluloses  which  have  been  treated  by  the  different  processes.  Cellulose, 
which  has  been  mercerized  and  washed  out,  or  has  been  converted  into  viscose 
and  regenerated,  is  not  so  reactive,  with  Fehling's  solution  for  instance,  as 
cellulose  that  has  been  treated  with  acid.  Cross  and  Bevan  have  proposed 
the  name  "  hydrate  cellulose  "  for  the  former  ;  whereas  the  latter  is  called 
"  hydro-cellulose. "•  Hydrate  cellulose  gives  off  its  extra  water  at  a  tempera- 
1  See  Denning,  ./.  Amer.  Chem.  Soc.,   litll,  p,   L515. 


1.54  EXPLOSIVES 

ture  of  12"  -125  .  whereas  hydro-cellulose  retail  -inatelv.  and 

at  this  temperature  gives  off  less  than  untreated  celluL  - 
Oxr-cellnkwe.         By  treatment  with  weak  nitric  acid,  potassium  permanganate,  bromine, 
and  other  oxidizing  agents  a  certain  amount  of  oxygen  is  caused  to  combine 
with  the  cellulose,  producing    *  oxy-cellulose."*  which  ale  .ore  reactive 

than  normal  cellulose. 
Hitro-oxy-  The  effect  upon  the  nitration  of  the  presence  of  these  various  abnormal 

cellulose,  etc.   ct.]ji;  g  formed  the  subject  of  a  number  of  investigations  of  recent  ye 

iclhaus  and  Vieweg  i  found  that  mercerization  does  not  affect  the  per- 
centage of  nitrogen,  but  considerably  increa-  -  lubility  in  ether-alcohol. 
Berl  and  Klaye   have  treated  cellulose   with  various  reagents,   nitrated 
them,  and  examined  the  products  before  and  after  nitration.3     The  following 
are  the  materials  they  experimented  with  : 

I    I  otton  wool  treated  with  2  per  cent,  soda  solution  to  remove  fat.  and 

-hed  with  hot  distilled  water  until  there  was  no  alkaline  reaction.     By 

combustion  analysis  it  was  found  to  contai  ,ier  cent.  C  and  6-35  per 

cent.  H  calculated  on  the  ash-free  material:    calculated  for  C^H^Cls  44  42 

per  cent.  C  and  ij-23  per  cent.  H. 

II.   Hydro-cellulose  made  by  dipping  the  above  in  3  per  cent,  solution 
dphuric  acid,  drying  and  heating  for  three  hours  at  70:  in  a  closed  v 
Found  42-75  per  cent.  C.  6-43  per  cent.  H  :    calculated  for  3C*H„0S  +  H  .<  » 
42-86  per  cent.  C.  6-35  per  cent.  H 

III  Hydral-cellulose  :  15  g.  cellulose  digested  with  30  c.c.  of  a  30  per 
cent,  solution  of  hydrogen  peroxide  for  thirty  days.  Found  43-24  per  cent. 
C.  6-25  per  cent.  H  :  calculated  for  4C«H1#0i  +  H_n  43  24  per  cent.  C.  6-30 
per  cent.  H. 

IV.  KM  32  g.  cellulose  treated  with  a  solution  of 
30  g.  permanganate  in  300  c.c.  water  for  thirty-six  hours  with  frequent  shak- 
ing. Then  decolorized  with  sulphurous  acid  and  digested  with  dilute  sulphuric- 
acid.  Dissolved  in  10  per  cent,  caustic  soda  solution  and  reprecipitated 
with  acid.  Found  43-61  per  cen*  I  per  cent.  H  ;  calculated  for  4CtH„Os 
-|-  C«H1#0«  43-58  per  cent.  I           I  per  cent.   H 

V.  Br-<  »xy-cellulose  :  25  g.  cellulose  allowed  to  >tand  for  a  day  with 
a  mixture  of  5  g.  bromine.  75  g.  calcium  carbonate  and  400  c.c.  water.  The 
bromine  was  then  driven  off  on  the  water-bath.  50g.  bromine  and  75  g. 
calcium  carbonate  again  added  and  the  mixture  shaken  in  a  machine.     Found 

S3  per  cent  :    per  cent.   H:    calculated  for  SCtH„Os  +  C\H„0, 

96  per  cent.  C.  611  per  cent.  H 

VI  'xy-cellulose :    5    g.    cellulose    allowed    to    stand    for    a 

week  with  22  g.  calcium  permanganate  and  water,  decolorized  with 

•   Ost  and  Westhoff.  C.Z.,  1909.  p.   197;    J     -  d.,   1909.  p.     . 

*  h  \   p.   441.  W  "p.   381. 


CELLULOSE 


155 


sulphurous  acid  and  washed.  The  permanganate  was  added  gradually. 
Found  ,43-52  per  cent.  C,  5-20  per  cent.  H  ;  calculated  for  3C6H10O5  +  CGH806 
43-51  per  cent.  C,  5-74  per  cent.  H. 

VII.  HN03-Oxy-cellulose  :  50  g.  cellulose  heated  on  a  water-bath 
for  two  and  a  half  hours  with  350  c.c.  nitric  acid  of  sp.  gr.  1-3.  Found 
43-17  per  cent.  C,  5-95  per  cent.  H;  calculated  for  2C6H10O5  -f  C6H806 
43-03  per  cent.  C,  5-98  per  cent.  H. 

i  VIII.  KClCvOxy-cellulose  :  30  g.  cellulose  heated  to  100°  with  a 
solution  of  150  g.  chlorate  in  3000  c.c.  water  and  135  c.c.  hydrochloric  acid 
(20°  B.)  gradually  added.  Found  43-34  per  cent.  C,  6-39  per  cent.  H  ;  calcu- 
lated for  3C6H10O5  +  C6H10O6  43-37  per  cent.  C,  6-02  per  cent.  H. 

IX.  Bleaching  Powder-Oxy-cellulose  :  cellulose  allowed  to  stand  in  the 
air  with  a  solution  of  bleaching  powder  of  10°  B.,  washed  with  slightly  acidified 
water,  dissolved  in  10  per  cent,  caustic  soda  solution  and  precipitated  with 
acid.  Found  43-62  per  cent.  C,  G-36  per  cent.  H  ;  calculated  for  4C6Hlll05 
+C6H10O5  43-58  per  cent.  C,  6-05  per  cent.  H. 

These  products  were  examined  also  as  to  the  colorations  they  gave  with 
various  reagents,  but  these  were  affected  to  a  considerable  extent  by  the 
different  physical  structures  of  the  materials. 


Ash 
per 
cent. 

Methylene 
blue,  mg. 
absorbed 

by  1  g. 

Coloration  with 

Microscopic  examination 

I  +  H2SO4 

I+ZnCl2 

Fehling 

solution 

I. 

Cellulose  . 

0-10 

3-7 

blue 

blue- 

7 

Normal. 

II. 
III. 

Hydro -cellulose 
Hydral-cellulose 

0-18 

(tin 

41 
6-5 

blue 
blue 

violet 
blue 

blue 

G 
4 

Fibres  partly  attacked, 

twisted. 
Structure  retained,  in- 

IV. 
V. 

KMn04-0/c.     . 
Br-0  c.    . 

0-96 
[•20 

4-4 

(HI 

blue 
pale  blue 

blue 
blue 

7 

1 

terference  colours. 
Granular  powder. 
Structure     almost    de- 

VI. 

Ca(Mn04)a  0  c. 

0-77 

6-7 

pale  brown 

blue 

5 

stroyed,  interference 
colours. 
Structure  little  changed. 

VII. 

HX03  ()  c. 

0-27 

6-8 

yellow  ish 

blue 

0 

strength  small. 
Structureless,          hard 

VIII. 

K('l()3-0/c,       . 

0-32 

9-5 

yellow-brown 

blue 

1 

grams. 
Broken    down,     inter- 

IX. 

Bleach.  Pow.O  c. 

0-55 

81 

pale  blue 

blue 

3 

ference  colours. 
Gran  ul  ir  powder. 

These  products  were  nitrated  with  acid  having  the  composition  : 

Per  cent,  by  weight  Molecular  per  cent. 

H2S04 46-22  ..  26-5 

HNO, 4203J 

-25  j 


NaO. 
H,0 


37-8 


11-50 


35-7 


]  56 


EXPLOSIVES 


for  twenty-four  hours  at  a  temperature  of  about  20°,  after  which  they  were 
washed  for  three  day-,  rir-t  with  cold  and  then  with  hot  water.  Ultimate 
analv>e-.  etc.,  were  made  of  the  nitro-celTulosee  : 


Ni". :    .                                                 from 

Solu- 

Methy- 

ana. 

bility 
in 

lene 
blue 

-in 

Nitro- 

Duma-        C  :  H              X  :  O 

Et.  Al. 

I.  ( fettul 

13-50 

13-32    24-0    34-0  :  11"  :  41  -8 

1-8 

10,000-0 

II.  Hydro -celh. 

13-23 

10-9    42-1 

12-15 

2-4 

3 

III.   Hydral-eell 

13-07 

—       24-0                10-6     41-2 

-. 

2-4 

81 

IV.  KMnO,-0  c    . 

13-31 

—       24-0:32-8:10-8:41-5 

180 

1  -6 

. 

V.   Br-0  c.  . 

12-92 

, 

15-5 

9-1 

VI.   (  a iMXOji,   1 

13-25 

—       24-0:35-5:10-8:41-4 

_ 

111 

VII.   HX<) ,-C)   c       . 

28     . .        34-0  :  10-4     *0-0 

34-0 

50 

7-9 

VIII.   K'                  .      . 

13-04 

—        24-0:  33-9  :  10-2  :  40-5 

180 

3-0 

-  •» 

Viscosity. 


The  following  were  the  resulte  of  tin-  microscopic  examination  : 

I.  Fibre-  intact,  in  polarized  light  steel  blue. 

11.  In  polarized  light  grey  fibres  as  well  a>  steel  blue. 

III.  Structure  retained,  in  polarized  li^rlit  Bteel  blue. 

IV.  In  polarized  light  blue. 

V.   In  polarized  light  blue  together  with  many  grey  li; 
VI.    Fibres  nearly  intact,  in  polarized  light   blue. 

VII.  Grains,  resolved  by  high  magnification  into  separate  fibres,  in  polar- 
ized light  blue  and  translucent  at  the 
VIII.   In  polarized  light  blue  with  violet  ti:  s 

In  the  case  of  No.  VII  the  atomic  ratio  i>  calculated  from  the  nitrogen 
determination  by  the  Dumas  method.  The  authors  do  not  consider  that  any 
conclusions  can  be  drawn  from  the  differences  in  the  nitrogen  determinations 
by  the  two  methods,  because  the  quantities  taken  for  analysis  were  in  - 
small.  The  increase  in  the  solubility  in  ether-alcohol  i>  no  a 
than  might  have  been  expected  from  the  Lower  percentage  of  nitrogen.  Tin- 
higher  ratio  of  oxygen  to  carbon,  which  was  t<>  be  observed  in  the  unnitrated 
products  after  treatment,  disappears  in  the  nitrated  products.  The  absorption 
of  basic  dye  i>  higher,  the  viscosity  much  lower  in  the  nitro-oxy-cellul 

than  in  the  nitro-cellulose.  The  viscosities  were  determined  with  2  per 
cent,  solutions  in  acetone  by  the  method  .if  Cochins.  For  comparison  a 
number  of  nitro-ceUulosefi  ed  by  nitrating  cotton  with    mixtures 


CELLULOSE 


157 


of  equal  weights    of  sulphuric  and  nitric  acids,   to  which    different    propor- 
tions of  water  were  added  :  J 


Per  cent,  water  in 

Per  cent.  N  in 

Methylene  blue 

Viscosity 

mixed  acid 

product 

absorbed 

11-50 

13-50 

0-63 

10,000-0 

13-20 

1302 

1-74 

578-0 

15-49 

12-48 

2-43 

503-0 

20-53 

10-41 

319 

56-0 

25-31 

9-09 

3-66 

15  0 

Xyloidine 

12-40 

— 

115 

Acetone 

1-09 

The  xyloidine  was  made  by  dissolving  in  sulphuric  acid  and  pouring  into  nitric 
acid. 

The  great  fall  in  the  viscosity  of  the  solutions  of  nitro-oxy-cellulose  as 
compared  with  nitro-cotton  indicates  that  the  size  of  the  molecules  has  been 
much  reduced. 

In  a  later  communication  2  Berl  returns  to  the  question  of  the  effect  of 
various  treatment  on  the  viscosity.  Cotton  which  had  been  mercerized  was 
nitrated  with  mixed  acid  of  practically  the  same  composition  as  that  used 
by  himself  and  Klaye  ;  the  product  contained  13-5  per  cent.  N.  This  was 
dissolved  in  acetone,  and  the  viscosities  were  compared  with  similar  solutions 
from  unmercerized  cotton : 


Nitro-cotton  from 


Mercerized 
cotton 

14 
122 


1  per  cent,  solution 

2  per  cent,  solution 

Merely  heating  the  nitro-cotton  reduces  the  viscosity  : 

Gun-cotton,  unheated     ..... 

,,  heated   for   3   hours  at    130°  . 


Unmenerized 
cotton 

1,378  sees. 

22,080    „ 


4-2()    sees. 
1-47      „ 


Heating  the  cotton  before  nitration  lias  a  similar  effect,  especially  if  oxygen 
be  present.  The  following  were  the  viscosities  of  1  per  cent,  solutions  of  the 
nitro-cottons  in  acetone  : 

Cotton  dried  but  not  heated      .......  2.'i.'!<>  sees. 

„      heated  60  hours  at  100°  in  atmosphere  of  oxygen     .          .  463  „ 

>>                  „                      „                          ,,               hydrogen.           .  1063  ,, 

»                „                    „                        „              carbon  dioxide  1110  ,, 

1  See  also  'I'.  Chandelon,  Bull.  Soc.  Chim.   Belg.,    MM 4.  28,  p.  24. 

2  S.S.,   1909,  p.  81. 


168 


EXPLOSIVES 


Over-bleached 
cotton. 


These  matters  are  of  some  practical  importance  as  different  degrees  of  viscosity 
are  required  for  different  purpoe 

The  effect  produced  by  heating  in  a  current  of  dry  oxygen  indicates  that 
oxidation  takes  place.  Cunningham  and  Doree  *  found  that  ozonized  oxygen 
has  a  very  powerful  effect  on  moist  cotton  at  the  ordinary  temperature,  form- 
ing a  peroxide  of  cellulose,  which  when  boiled  with  water  gave  an  oxy-cellulose 
with  a  copper  value  of  15  to  IT. 

The  nitration  of  cotton  that  has  been  over-bleached  has  been  studied  by 
Piest.2  as  also  that  of  cotton  that  has  been  mercerized  and  heated  to  a  high 
temperature.  The  experiments  were  done  on  a  manufacturing  scale  and  the 
nitro-celluloses  wen-  te-ted  for  stability.  Tire  results  of  the  bleaching  were 
as  follows  : 


Con- 

Experi- 
ment 

Treatment 

Fat 

Ash 

Wood- 
gum 

Copper 
value 

sump- 
tion of 

X/2 
NaOH 

Standard 

Normally  prepared  cotton 

•24 

•37 

n-92 

1-85 

1-6 

la. 

24  hours  with  bleaching  powder  solu- 
tion of  31     B. 

•1.-. 

•44 

2-86 

2-17 

— 

lb. 

48  hours  with  bleaching  powder  solu- 
tion of  3ic  B. 

■10 

-64 

4  04 

3-40 

2-8 

Ha. 

8    days    with    solution    of    2i    kg. 
bleaching  powder  in  50  1. 

•11 

•60 

813 

10-73 

5-2 

Ob. 

8  days  with  solution  of  5  kg.  bleach- 
ing powder  in  50  1. 

■10 

•85 

104 

16-3 

6-4 

Of  these  material-  la  and  lb  were  white:  Ha  was  yellowish-white  and  the 
fibre-  were  Bhort  ;  Hb  was  yellowish  and  consisted  of  particles  adhering  tightly 
to  one  another.     They  were  nitrated  with  acid  of  the  composition  : 


HXO, 

H  0   . 


By  v 

.     20-6 

.      690 
10-5 


Molecular 
Per  cent. 

20-2 

43-6 
36-2 


The  time  of  nitration  had  to  be  varied  in  order  to  ensure  that  the  acid  had 
penetrated  to  the  interior  of  the  fibres  in  all  cases.  After  nitration  the 
material  was  washed  first  with  cold  and  then  with  successive  lots  of  hot  water 
in  a   hollandti. 


1   T<  '  -  I'M  2.    pp.    4'.'7    :.12. 


2  A»  :..    L909,   p.    121"'. 


CELLULOSE 


159 


Experi- 
ment 

Time 
of 

nitra- 
tion 

N 

Solubility  in 

No. 

of 

hot 

washes 

Stability 

Ether-alcohol  after 

Abso- 
lute 
alcohol 

B.J. 
method 

Ober- 
miiller 
method 

First  cold 
wash 

Last  hot 

wash 

Hours 

Per  cent. 

c.c. 

mm. 

Standard 

\ 

1307 

— 

6-0 

2-40 

7 

3-4 

119 

lb. 

4* 

12-84 

18-8 

26-8 

4-75 

27 

8-3 

148 

Ha. 

1 

12-91 

21-8 

24-0 

3-34 

36 

5-7 

167 

lib. 

n 

12-72 

33-4             40-9 

9-00 

25 

1-6 

117 

The  number  of  hot  washings  required  to  obtain  a  satisfactory  stability  was 
much  higher  in  the  case  of  the  bleached  cottons,  but  as  judged  by  the  Berg- 
mann-Junk  test  none  of  the  nitro-celluloses  was  really  stable  except  the 
last,  for  the  official  limit  in  Germany  is  3  c.c,  and  a  good  gun-cotton  does  not 
give  more  than  2. 

Similar  experiments  were   carried  out  with   mercerized  cotton  and  cotton  Nitrated  mei 
that  had  been  heated  at  150°  in  a  current  of  CO*  : 


cerized  cottoi 


Experi- 
ment 

Treatment 

Fat 

Ash 

Wood- 
gum 

Copper 
value 

Standard 

Normally  prepared  cotton 

■23 

•28 

1-44 

1-77 

IV. 

Mercerized  20  minutes  with  18-5  per 

cent,  soda  lye     .... 

•16 

•25 

0-21 

1-59 

Via, 

Heated  10  hours  in  CO,  at   150°     . 

•23 

•23 

1-52 

1-69 

VIb. 

Heated  100  hours  in  CO,  at   150°  . 

•42 

•25 

2-44 

2-29 

The    heated    cottons    were    yellowish-white    and    yellow    respectively.     The 
following  were  the  results  of  nitration  : 


t-,                      Time 
Experi-                 r 

ment              -.      .. 

nitration 

N 

Solubility  in                                                Stability 

No. 

Ether- 
alcohol 

of 

Absolute        J"*               B.J. 
alcohol                               method 

Ober- 
miiller 
method 

Hour 
Standard             \ 
IV.                    1 
Via. 

Per  cent. 
1307 
12-96 
13-32 

60 

21-8 

4-9 

2-40                 7 
3-82               17 
1-72                 9 

c.c. 
3-4 
4-4 
3-8 

mm. 
119 
131 

160  EXPLOSIVES 

Mercerization  reduced  the  percentage  of  nitrogen  only  to  a  slight  extent. 
but  greatly  Increased  the  Bolubility  in  ether-alcohol  and  impaired  the  stability  ; 
it  also  increased  the  quantity  of  unnitrated  material  as  determined  by  treating 
the  nitro-cellulose  with  sodium  sulphide  solution.  In  the  nitrated  mercerized 
cotton  this  amounted  to  1-s  per  cent.,  whereas  in  all  the  other  of  the  above 
products  it  varied  between  0-6  and  0*8  per  cent.  Heating  the  cotton  in  carbon 
dioxide  made  very  little  difference  to  the  nitro-cotton,  but  it  was  somewhat 
more  difficult  to  stabilize. 

The  general  conclusion  from  this  investigation  is  that  both  over-bleaching 
and  mercerization  have  a  very  bad  effect  on  cotton  intended  for  the 
manufacture  of  nitro-cotton. 

Rest  has  also  investigated  the  action  of  alkalis  and  ammonium  sulphide 
solution  on  nitro-celluloses  prepared  from  normal,  over-bleached  and  mer- 
cerized cotton.1  He  found  that  the  material  from  over-bleached  cotton 
withstood  these  reagents  less  well  than  ordinary  gun-cotton,  but  that  the 
material  from  mercerized  cotton  withstood  them  somewhat  better.  The 
regenerated  cellulose  had  a  much  higher  copper  value  than  the  original  cottons, 
whence  Piest  concludes  that  it  has  been  converted  into  oxy-cellulose.  but 
does  not  consider  whether  it  may  not  rather  be  hydro-cellulose.  Vignon  2 
similarly  found  that  nitrated  hydro-cellulose  was  more  attacked  by  caustic 
pota-h  Bolution  than  normal  nitro-cellulose,  and  nitrated  oxy-cellulose  >till 
more. 

Vignon  3  considers  that  ordinary  gun-cotton  is  really  nitro-oxy-cellulose. 
He  prepared  the  product  of  maximum  nitration  according  to  Lunge's  direc- 
tions and  made  an  elementary  analysis  of  it.  The  results  were  in  accord 
with  the  formula  2CJEL^SO%)fit  +  C,H7(NOa),0,.  But  this  view  is  not 
generally  accepted.  The  cellulose  could  only  be  oxidized  by  the  nitric  acid, 
some  of  which  would  be  reduced  to  nitrous  acid,  whereas  there  is  practically 
no  formation  of  nitrous  acid  in  the  nitration  process.  Moreover,  there  are 
distinct  differences  between  the  nitration  products  of  normal  and  oxy- 
cellulose. 
Effect  of  dilute  As  regards  the  effect  upon  cotton  of  treating  it  with  dilute  caustic  soda 
lyes  of  different  strengths  and  at  different  temperatures,  some  curious  observa- 
tions have  been  made  by  Schwalbe  and  Robinoff.4  They  tried  the  effect  upon 
pure  cotton  cellulose  which  had  been  prepared  by  Tamin's  method  5  by  boil- 
ing with  a  solution  of  resin  soap  and  alkali  without  pressure,  washing  hot 
and  bleaching  very  carefully  :  in  this  way  they  obtained  a  material  which 
had  a  copper  value  of  only  0*042. 

1  Ang.,    1910,  p.    1009.  -  C.R..    1898.  p.    1658. 

3  Compt.  Rend..   138,   1904,  p.   398.  Ang.,   1911,  p.  256. 

•  Re*:  mat.  eol..    1908.   p.   313. 


CELLULOSE 


161 


Soda 
per 
cent. 

0 
1 
2 
3 
4 
5 
7 

Cotton 
dissolved 

Copper  values 

Temp. 
20° 

Temp. 
20° 

•042 
■150 

•166 
•195 
•257 
•135 
•154 

Temp. 
100° 

Temp. 
135° 

Temp. 

150° 

Temp. 
179° 

•30 

•11 
•128 
•445 
•05 

Temp. 
213° 

•74 
•53 
•49 
•42 
•34 
•14 

•109 

•180 

•20 

•262 

•528 

•168 

•153 
•142 

•17 
•395 

•89 

•285 

•190 

•10 
•15 
•28 
•70 
•12 

0 

When  an  over-bleached  cotton  is  heated  with  water  under  pressure  to  a 
temperature  above  150°  there  is  a  great  increase  in  the  copper  value  : 

Temperature  Copper  value 

20°  .  .  -368 

100°  . .  -312 

120°  ..  -331 

135°  . .  -40 

150°  . .  -479 

165°  .  .  1-43 

179°  ..  1-78 

213°  ..  3-43 

The  authors  conclude  that  the  strength  of  the  soda  used  for  the  purification 
of  cotton  should  never  be  allowed  to  fall  below  5  per  cent,  and  should  be  made 
up  from  time  to  time  to  this  strength  if  necessary,  also  that  temperatures 
above  150°  should  not  be  employed.  They  also  found  that  the  acid  for  sub- 
sequently acidifying  need  not  be  of  greater  strength  than  0-1  per  cent.  ;  with 
weaker  acid  the  cotton  is  even  whiter  but  the  copper  value  is  higher. 

It  has  been  found  by  Trotman  x  that  the  addition  of  neutral  salts  to  soda 
lye  considerably  reduces  the  loss  of  weight  of  cotton  boiled  in  it,  and  hence  he 
concludes  that  the  purification  of  the  cotton  is  interfered  with  by  the  presence 
of  these  salts. 

Von  Lenk  for  his  gun-cotton  used  cotton  in  the  form  of  hanks  of  yarn.  Cotton  use 
When  Abel  had  discovered  the  very  beneficial  effect  of  pulping  the  gun-cotton  manufactl] 
there  was  no  longer  any  object  in  using  such  an  expensive  variety  of  raw 
material,  and  he  used  instead  cotton  waste,   the  residual  cotton  from  the  Cotton  wa 
spinning-mills.     In  the  early  days  of  the  industry  there  was  little  demand 
for  this  material  and  the  cotton  waste  supplied  to  the  explosives  industry 
was  generally  of  good  quality,  but  in  course  of  time  the  demand  for  cotton 
1  J.  Soc.  Chem.  Ind.,   1910,  p.  249. 
VOL.  I.  II 


EXPLOSIVES 

waste  not  only  for  the  manufacture  of  nitro-cotton  but  also  for  other  pur] 
grew,  and  it  is  now  difficult  to  obtain  a  really  satisfactory  cotton  waste.     More- 
over, a  special  industry  has  sprung  up — the  cotton-waste  industry — which 
collects  the  waste  from  all  the  mills  and  prepares  it  for  various  purp 
The  object  of  the  suppliers  of  cotton  waste  is  to  produce  a  material  that  will 

n  ■  specification,  rather  than  to  supply  a  really  good  cotton  which  can  be 
made  into  stable  gun-cotton,  a  matter  about  which  of  course  they  know  little 
or  nothing.  Cotton  waste  for  nitrating  is  made  largely  from  the  sweepings  of 
the  cotton-mills  ;  it  contains  some  spun  thread,  but  it  is  liable  to  consi-t 
largely  of  "  fly.'*  the  fluffy  material  which     -  a  into  the  air  during  the 

various  mechanical  operations.  This  fly  is  the  least  resistant  portion  of 
the  cotton  as  it  is  supplied  to  the  mills.  The  presence  of  a  very  large  pro- 
portion of  dirt  and  oil  and  all  manner  of  foreign  matter  makes  it  necessary 

submit  the  cotton  waste  to  a  very  drastic  scouring  and  bleaching  pro  se 
and  this,  as  may  be  seen  from  the  preceding  pages,  must  inevitably  produce 
a  considerable  proportion  of  oxy-cellulose  and  other  modifications  of  the 
normal  resistant  cotton  cellulose.  At  the  same  time  more  and  more  demands 
are  being  made  upon  the  stability  of  the  nitro-cottons.  especially  those  used 
for  the  manufacture  of  smokeless  powders  for  military  and  naval  pur]"  m  -. 
sequently  the  explosives  works  have  been  obliged  to  give  more  attention 
to  the  question  of  their  supplies  of  cotton.  A  few  of  the  largest  obtain  their 
cotton  waste  unpurified  and  uncleansed  from  the  mills  and  purify  it  them- 
selves, and  undoubtedly  this  is  the  best  method  where  it  is  practicable. 

?te  from  weaving  mills  might  also  be  used  for  making  nitro-cotton. 
but  it  is  liable  to  be  contaminated  with  starch,  which  is  applied  to  the  warps 
to  increase  their  strength.  Starch  on  nitration  gives  an  unstable  nitration 
product,  and  consequently  must  be  removed  from  the  cotton  by  suitable 
treatment.  New  cotton  can  also  be  used,  the  only  objection  to  it  being  its 
high  price  :  its  employment  for  the  manufacture  of  smokeless  powder  would 
only  involve  slight  alterations  to  the  dies.  etc. 

The  cotton  is  subjected  to  various  purification  proc tore  it  can  be 

To  remove  the  greater  part  of  the  oil  and  fatty  matter  it  Le 
tracted  with  a  volatile  solvent  in  an  extraction  vessel  The  solvent  after 
it  has  soaked  through  the  cotton  flows  into  a  chamber  where  it  is  boiled  by 
means  of  steam  pipes  :  the  vapour  is  condensed  and  again  flows  through 
the  cotton.  When  the  extraction  is  finished  the  solvent  is  distilled  off  into 
a  receiver  and  the  last  portions  of  it  are  removed  from  the  cotton  by  blow- 
ing steam  through  it.  A  -nt  benzine  or  benzol  can  be  used  :  both  are 
very  inflammable  and  somewhat  poi-  -  ind  precaution-  should  be  taken 
accordingly.  Carbon  bisulphide  is  still  more  inflammable.  Carbon  tetra- 
chloride and  other  chlorinated  carbon  compounds  are  not  imflammabk-.  but 
are  more  poisonous  than  benzine  or  benzol.     The  choice  of  the  solvent  will 


CELLULOSE  163 

depend  on  the  price  and  the  local  conditions.  After  extraction  the  cotton 
is  boiled  in  a  kaer  with  a  weak  solution  of  caustic  soda  or  sodium  carbonate, 
and  well  washed  with  water  either  in  the  kier  or  in  a  poacher.  After  this  it 
is  generally  bleached  with  a  weak  solution  of  bleaching  powder  or  sodium 
hypochlorite.  This  operation  is  often  carried  out  in  stone  cisterns,  but  if 
the  bleaching  solution  be  very  weak  iron  vessels  can  be  used.  Next  it  is 
treated  again  with  dilute  alkali  to  destroy  the  bleach  and  then  washed  again 
thoroughly.  The  bulk  of  the  water  is  then  removed  in  a  centrifugal  machine 
and  the  cotton  is  finally  dried  and  made  into  bales.  It  is  important  that 
cotton  whilst  alkaline  be  not  exposed  to  air  at  a  high  temperature. 

For  the  removal  of  the  fatty  matters,  soaps,  especially  resin  soaps,  can 
be  used.  The  whole  purification  process  can  be  varied  in  many  different 
ways,  and  must  be  adapted  to  the  sort  of  cotton  that  is  to  be  treated.  It  is 
required  to  remove  all  matters  except  normal  resistant  cellulose,  without 
injuriously  affecting  the  character  of  the  latter.  Although  the  methods  of 
treating  ordinary  cotton  goods  have  formed  the  subject  of  numerous  investiga- 
tions, the  preparation  of  cotton  for  nitration  has  not  received  the  attention 
which  its  importance  calls  for. 

B.  S.  Levine  recommends  treating  the  cotton  with  bacteria  instead  of 
bleaching.     He  claims  that  the  impurities  are  thus  removed  more  completely.1 

For  the  manufacture  of  collodion  cotton  for  blasting  gelatine  cop-bottoms  Cop-botton 
are  generally  used.     This  is  spun  thread  in  a  tangled  condition,  the  last  portion 
left  on  the  spindle.     This  undoubtedly  is  a  very  good  class  of  material,  but 
is  usually  considered  too  expensive  for  the  manufacture  of  smokeless  powder. 

After  the  long  staple  fibres  or  "lint"  have  been  removed  by  the  first  ginning,  Linters. 
there  is  on  American  upland  cotton  seed  still  about  10  per  cent,  of  short  fibre 
cotton,  which  is  recovered  by  a  second  process,  and  is  known  as  "  linters." 
From  "  sea-island  "  cotton,  which  is  grown  near  the  coast,  and  Egyptian 
cotton  long  staple  fibres  only  are  obtained,  and  consequently  these  varieties 
yield  no  linters.  This  would  form  quite  good  material  for  the  manufacture 
of  nitro-cotton,  if  it  could  be  freed  mechanically  from  the  adherent  resin  and 
all  particles  of  seed-husk,  but  this  does  not  appear  to  be  possible,  and  conse- 
quently the  linters  have  to  be  submitted  to  a  very  drastic  chemical  treatment, 
which  damages  the  cellulose.  Moreover  the  seeds  often  remain  for  a  long 
time  before  the  linters  are  removed  and  during  this  time  they  undergo  a  certain 
amount  of  fermentation  and  the  fibre  is  attacked.2  When  nitrated  linters 
consequently  give  somewhat  low  nitrogens  and  high  solubilities  in  ether-alcohol. 
They  are,  however,  used  on  a  considerable  scale  in  America  and  Germany, 
but  not  so  much  in  England. 

For  the  manufacture  of  collodion  for  high-class  lacquers  and  celluloid,  Tissue  pap< 
cellulose  is   used   in   the  form   of  tissue   paper.     Although   this  is  somewhat 
1  J.  hid.  Eng.  Ghem.,   1910,  p.  298.  2  Rest,  Ang.,  19.12,  p.  396. 


164  EXPLOSIVES 

expensive,  it  has  great  advantages  for  this  class  of  work  :  by  inspection  of 
the  sheets  it  is  possible  to  detect  and  then  to  remove  every  (Article  of  foreign 
matter.  Moreover,  these  thin  Bheets  are  nitrated  completely  in  a  very  short 
time.  The  paper  must,  of  course,  consist  of  pure  cellulose  and  should  not 
be  calendered. 

Schuitze  sporting  powder  has  always  been  made  from  purified  wood  fibre, 
and  the  makers  claim  that  this  gives  a  powder  with  the  right  rate  of  burning 
more  readily  than  cotton.  Other  makers  of  "  bulk  "  shot-gun  powders  have 
also  used   nitrated   wood   cellulose. 

Wood-cellulose,  or  chemical  wood-pulp,  is  made  by  three  different  methods 
called  the  sulphite,  Boda  and  sulphate  processes.  In  all  of  these  finely  ground 
wood  pulp  is  boiled  with  a  solution  which  destroys  the  non-cellulose.  In  the 
sulphite  process  a  solution  of  calcium  or  sodium  bisulphite  is  used,  in  the  Boda 
process  caustic  soda,  and  in  the  sulphate  process  a  3<  lution  of  caustic  a  da 
and  sodium  sulphide. 

A  number  of  wood  and.  straw  celluloses,  and  nitro-celluloses  prepared  from 
them,  have  been  examined  by  Nitzelnadel.1  The  wood  celluloses  were  pre- 
pared by  the  sulphite  process,  the  straw  celluloses  by  the  sulphate  pro 
None  of  the  latter  proved  satisfactory,  but  one  of  the  sulphite  celluloses  gave 
a  good  yield  of  nitro-cellulose.  which  could  be  rendered  -table.  ( '.  B.  Schwalbe 
and  A.  Schrimpf  -  have  also  prepared  mtro-celluloses  in  the  laboratory  from 
wood  celluloses  made  by  different  processes  from  various  woods.  They 
obtained  nitro-celluloses  of  a  high  degree  of  nitration  and  satisfactory  stability 
bo  far  as  the  tests  could  show.  For  the  preparation  of  high-class  Bmokeless 
powder  for  rifled  fire-arms  it  would  be  necessary  to  purify  the  wood  cellulose 
vers-  carefully  and  to  make  it  into  thinner  sheets  than  is  usual.  Under  normal 
conditions  this  must  make  the  wood  cellulose  almost,  if  not  quite,  as  expen- 
sive as  the  cotton  waste  generally  employed,  and  as  the  true  stability  of  the 
smokeless  powder  can  only  be  ascertained  by  keeping  trials  extending  over 
many  years,  it  is  easy  to  understand  that  most  of  the  Powers  have  not  used 
it  for  their  powders.  The  Japanese,  however,  are  said  to  be  using  wood  cellu- 
lose from  Sakhalin.3  and  it  is  probable  that  the  Germans  are  using  it.  since 
they  can  no  longer  import  cotton. 

Cellulose  is  attacked  by  various  bacteria,  especially  if  it  be  mixed  with 
substances  which  provide  food  that  favours  their  development.  The  methane 
which  rises  from  marshes  i-  apparently  derived  principally  from  the  fermenta- 
tion of  cellulose  :  the  intestines  of  animals  also  contain  bacteria  and  ferment-, 
which  attack  cellulose.  Even  pure  cotton  cellulose  can  lie  thus  entirely 
destroyed;    Hoppe-Seyler  4  found  that  Swedish   tilier-paper  was  completely 

1  S.S.,   1912,  pp.  257,  301,  :;:;'.'.  384  and  409.  ■  Ang.,   1914,  p.  662. 

3  A.  Buisson,  Le  Probleme  des  I'oudrcs,  Paris,    I'M'!,  pp.    17.">.    177. 
*  Z.  physiol.   Ch.,   10,  p.  401. 


CELLULOSE  165 

resolved  into  gaseous  products  in  the  presence  of  river  mud.  He  considered 
that  cellulose  was  first  hydrated  C6H10O5  -j-  H20  =  C6H1206,  and  was  then 
converted  into  methane  and  carbon  dioxide,  C  6H  j  20  6  —  3C0  2  +  3CH4. 
Omelianski  l  found  two  different  ferments  in  river  mud,  one  of  which  produced 
hydrogen,  and  the  other  methane.2  The  bacteria  were  anaerobic,  but  aerobic 
organisms  capable  of  destroying  cotton  and  linen  have  been  found  by  Herson. 

If  cotton  be  stored  for  a  long  time  under  unfavourable  conditions  as  regards 
heat  and  moisture,  it  is  liable  to  be  affected  injuriously.  In  extreme  cases 
it  may  become  quite  friable  and  dusty,  but  even  before  this  stage  is  reached 
it  is  unsuitable  for  the  production  of  stable  nitro-cotton,  probably  on  account 
of  the  formation  of  hydrated  cellulose.  If  such  a  material  be  nitrated  and  stored 
for  some  time  in  a  warm  place  it  undergoes  decomjjosition  with  the  forma- 
tion of  a  considerable  amount  of  water  and  other  decomposition  products. 

The  micro-photographs  (Fig.  30)  reproduced  from  a  paper  by  de  Mosenthal 3 
show  very  clearly  the  structure  of  the  cotton  fibre.  In  Xo.  1  the  characteristic  structure  i 
twisting  of  the  fibre  is  seen  ;  Nos.  2,  3,  5  reveal  the  pores  through  the  outer  cotton  flbr 
cutieb.  No.  4,  a  longitudinal  section  of  the  fibre,  is  almost  unique  on  account 
of  the  extreme  difficulty  of  obtaining  such  a  view  ;  it  clearly  shows  the  inner 
and  outer  cuticles  and  the  matter  in  the  centre  of  the  tube.  The  material 
forming  the  greater  part  of  the  walls  of  the  tubes  consists  of  true  cellulose. 
It  is  granular  in  structure  and  is  held  in  position  by  the  inner  and  outer  cuticles, 
which  exert  so  much  pressure  on  it  that  the  fibre  is  seen  to  be  doubly  refract- 
ing when  examined  in  polarized  light.  If  one  of  the  cuticles  be  removed  so 
as  to  relieve  the  pressure,  colours  are  no  longer  seen  under  the  polarizing 
microscope.  When  treated  with  dilute  soda  and  bleaching  solution,  the 
compound  cellulose  of  the  outer  cuticle  is  no  doubt  attacked  to  a  considerable 
extent,  but  the  inner  cuticle  and  the  matter  in  the  interior  of  the  tube  cannot 
be  reached  so  well  by  the  solutions,  and  consequently  must  escape  treatment. 
De  .Mosenthal  observed  that  a  single  fibre  has  no  capillary  action,  but  when 
several  are  bundled  together  liquids  are  drawn  up  between  them.  This 
indicates  that  there  is  no  free  passage  up  the  centre  of  the  fibre  ;  that  the  tube 
is  obstructed  at  intervals.  The  material  in  the  centre  of  the  fibre  probably 
gives  rise  to  unstable  products  on  nitration,  and  it  is  perhaps  the  function  of 
the  pulping  process  to  render  it  possible  to  remove  these  partly  from  the 
nitro-cotton. 

When  treated  with  cuprammonium  solution  (Schweitzer's  reagent),  the 
cuticle  dissolves  much  less  readily  than  the  bulk  of  the  fibre  (see  No.  5,  Fig.  30), 
and  the  same  thing  occurs  when  nitro-cotton  is  dissolved  in  acetone  or  other 
solvents.     When  passed   through  a   Pasteur  filter  these  particles  of  cuticle 

1  Compt.   Rend.,   121,   1905,  p.  653. 

-  Sk    also  Lafars  Handbuvh  <l<  r  technischen  Mykologie,  Bd.   •'!.    Kap.  9. 
a  J    Soc.  Chem.  Ind.,   1904.  p.  292. 


I.  Natural  Cotton   Fibre       300 


2.   Portion  of  Bame  Fibre        1000 


Portion  of  (2)  Focused  to  Show   Stomata        L000  4.  Longitudinal  Section  of  Cotton   Fibre  x  1000 


a    , 

i 

a 

■ 

a 

a 

/  . 

a 

•  m 

/ 

i      o 

•..%. 

- 

• 
- 

■ 

•>      . 

\ 

. 

5.  Portion  of  a  Fragment  of  Cotton 

Cuticle  from  a  Solution  in  Cuprammo 

uium  X  1100 

a  .  .  .  .  indicates  the  Stomata 


6.  Granules  from  a   6j  per  cent.  Solution 
of  Nitrated  Cotton  X  1600 


7.  Portion  of  a  Nitrated  Cotton   Fibre       300 
Fig.  30.     Microphotograpli-  of  Cotton  ('!«•  Rosenthal), 


CELLULOSE  i6? 

are  removed  from  the  solutions  to  a  great  extent.  For  the  manufacture  of 
artificial  silk  such  filtration  is  necessary,  because  otherwise  the  orifices  of  the 
"  silk-worms  "  get  stopped  up.  It  is  somewhat  remarkable  that  the  molecules 
of  nitro-cellulose,  which  must  be  very  large,  can  pass  through  the  minute 
pores  of  a  Pasteur  filter,  which  stop  the  molecules  of  many  organic  dye-stuffs . 
It  can  only  be  explained  on  the  assumption  that  the  cellulose  molecule  is  in 
the  form  of  a  long  string.  The  molecules  of  nitro-cellulose  will  not  pass  through 
a  dialyzer.1 

When  cotton  is  nitrated  the  pressure  exerted  by  the  cuticle  is  released, 
with  the  consequence  that  the  twists  of  the  fibres  disappear  (sec  No.  7),  and 
the  interference  colours  become  much  less  brilliant.  Similar  changes  in 
appearance  occur  when  cotton  is  mercerized  or  submitted  to  other  actions 
of  a  like  nature. 

All  cotton  contains  a  proportion  of  immature  fibres,  called  dead  or  unripe  Dead  colt 
cotton.  These  have  very  thin  walls  and  either  no  central  channel  or  a  very 
flat  one.  They  are  weak  and  consequently  liable  to  break  during  the  spinning 
operations.  Therefore  they  constitute  a  large  proportion  of  the  "  fly  "  which 
passes  into  the  cotton  waste.  It  is  less  easily  nitrated  or  acetated  than  ripe 
cotton.  It  generally  has  a  smaller  twist,  but  the  fibres  retain  this  twist  on 
treatment  with  an  18  per  cent,  solution  of  caustic  soda.  It  behaves  differently 
with  dye-stuffs  also. 

If  the  cotton  bolls  be  allowed  to  remain  on  the  plant  for  some  time  after 
they  are  ripe  the  cotton  acquires  characters  very  similar  to  these.  Cotton 
is  liable  to  form  in  portions  of  the  length  of  the  fibre  solid  parts,  which  do  not 
take  up  dye  properly.  This  is  usually  at  the  tip,  which  is  consequently  brittle 
and  breaks  off  during  the  spinning  processes.  In  the  body  of  the  fibre  this 
structure  is  seldom  found  except  in  the  coarser  varieties,  such  as  Surat  and 
Peruvian.2 

1  De  Mosenthal,  J.  Soc.   Chem.  Ind.,   1907,  p.  447. 

2  F.  H.  Bowman.  Structure  of  the  Cotton  Fibre,  p.  113.  See  also  Chem  Zeit.,  Sept., 
1915. 


CHAPTER    XII 
MANUFACTURE   OF  NITRO-CELLULOSE 

Picking  the  cotton  :  Teasing  :  Drying  :  Nitrating  :  Abel's  pro.  mfugal 

process  :  Direct  dipping  :  Displacement    process  :  Hyatt  nitrator  :  High  nitrogen 
gun-cotton   :  Partially    soluble     nitre-cottons  :   Soluble    nitro-cottons  :  Pyro- 
collodion   :   Collodion  for  blasting  gelatine   :  Collodion  for  other  purp 

When  the  raw  material  used  is  purified  cotton  waste.,  it  is  necessary  to  pick 
it  over  first  by  hand  in  order  to  remove  all  string,  pieces  of  wood  and  metal, 
hard  knots  of  cotton  and  all  other  matter  which  would  not  nitrate  satisfactorily. 
This  work  is  generally  clone  by  women. 

Next  the  material  must  be  opened  out  by  means  of  a  teasing  machine. 
The  simplest  form  of  this  consists  of  a  rapidly  rotating  drum  armed  with 
numerous  iron  teeth  and  a  pair  of  feed-rollers  that  grip  the  unteased  cotton 
firmly  and  gradually  feed  it  up  to  the  drum,  which  tears  it  off  in  small  portions 
and  throws  it  out  at  the  other  side  of  the  machine.  The  whole  should  be 
enclosed  to  prevent  the  fine  cotton  dust  riving  about. 

The  cotton  as  supplied  generally  contains  about  x  per  cent,  of  moisture. 
and  it  is  desirable  to  reduce  this  to  about  0-5  per  cent.  This  may  be  effected 
in  any  ordinary  form  of  stove.  The  simplest  type  is  a  cupboard  with  a  number 
of  perforated  shelves  on  which  the  cotton  is  placed,  and  steam-pipes  under- 
neath. Suitable  openings  allow  hot  air  to  circulate  through  the  cotton  and 
escape  at  the  top  of  the  cupboard.  The  disadvantage  of  this  form  is  that 
the  cotton  in  the  lower  trays  gets  much  hotter  and  dryer  than  that  in  the 
top  ones.  Instead  of  having  the  steam-pipes  underneath  they  may  be  in  a 
separate  heater  through  which  air  is  forced  by  means  of  a  fan  and  then  through 
lli  •  stove,  but  the  utilization  of  the  heat  is  not  very  good,  as  the  air  is  cooled 
down  before  it  can  take  up  more  than  a  small  proportion  of  water.  In  the 
most  economical  Btoves  these  two  method-  of  heating  arc  combined,  that  is 
to  say  the  air  is  blown  through  a  heater  into  the  stove,  which  ifl  provided  with 
a  number  of  steam-pipes,  which  maintain  the  temperature  at  about  90°  C. 
The  cotton  should  be  made  to  pass  continuously  through  the  stove  by  means 
of  travelling  bands.  The  drying  takes  about  three-quarters  of  an  hour  Over- 
heating or  too  prolonged  drying  should  be  avoided. 

168 


MANUFACTURE   Oft  NITROCELLULOSE  169 

The  method  of  nitration  worked  out  by  Baron  von  Lenk  was  described  Nitrating, 
at  length  in  the  paper  published  by  Abel  in  the  Proc.  Roy.  Soc,  1866,  p.  269. 1 
This  was  only  slightly  modified  by  Abel,  and  was  followed  at  Waltham  Abbey 
and  in  other  factories  until  recently,  the  principal  difference  made  being  the 
use  of  cotton  waste  instead  of  the  skeins  of  yarn  used  by  von  Lenk.  The 
method  as  carried  out  at  Waltham  Abbev  until  1905  was  described  thus  by 
Sir  F.  L.  Nathan  :  2 

The  nitrating  acid  was  composed  of  three  parts  of  sulphuric  acid  of  96  Abel's  pro 
percent,  mono-hydrate  to  one  part  of  nitric  acid  of  91  per  cent,  mono-hydrate, 
thoroughly  mixed  and  cooled.  This  acid  was  run  from  the  store  tanks  into 
cast-iron  dipping  pans,  holding  about  220  lb.  each,  the  pans  being  supported 
in  an  iron  tank  through  which  cold  water  circulated  to  keep  the  temperature 
below  70°  F.  The  dipping  pans  were  provided  at  the  back  with  gratings, 
on  which  to  press  out  some  of  the  acid  from  the  charge.  The  charge  of  cotton 
waste  weighed  1  lb.  4  oz.,  and  on  removal  from  the  cooling  box  was  passed 
from  the  back  through  an  earthenware  pipe  in  the  partition  running  along 
the  back  of  the  pans,  and  raked  by  a  dipper,  as  rapidly  as  possible,  into  the 
acid.  After  remaining  in  the  acid  bath  for  about  eight  minutes  the  cotton 
was  removed  to  the  grating,  and  a  portion  of  the  acid  squeezed  out  by  means 
of  an  iron  lever  having  an  iron  plate  attached  to  one  end.  After  a  charge 
had  been  removed  from  the  dipping  pan  about  13|  lb.  of  the  mixed  acid  was 
run  into  it  to  replace  the  amount  removed  with  the  charge.  The  charge, 
now  weighing  with  the  adhering  acid  about  15  lb.,  was  placed  in  an  earthen- 
ware pot  provided  with  a  cover  and  transferred  to  the  cooling  pits,  through 
which  a  stream  of  cold  water  flowed,  and  where  it  remained  for  twelve  hours. 
During  this  period  of  digestion  the  conversion  of  the  cotton  into  gun-cotton 
was  completed.  The  contents  of  the  pots  were  now  emptied  into  a  centrifugal 
wringing-machine,  and  the  bulk  of  the  waste  acid  extracted.  The  gun-cotton 
was  then  removed  from  the  centrifugal  machine  and  placed  in  galvanized 
iron  pans  with  long  handles.  These  pans  when  filled  were  carried  quickly 
across  to  the  immersing  tank,  and  the  gun-cotton  thrown  into  a  large  bulk 
of  water,  the  workmen  standing  by  the  tank  and  pushing  the  gun-cotton  at 
once  under  the  water  with  a  stout  wooden  paddle.  The  immersing  had  to 
be  done  as  quickly  as  possible,  as,  if  the  gun-cotton  were  allowed  to  come 
gradually  in  contact  with  water,  it  was  liable  to  fume  off.  The  immersing 
tank  was  fitted  with  a  perforated  copper  plate  to  allow  the  water  to  overflow, 
so  that  fresh  water  was  constantly  passing  through  the  tank.  The  gun-cotton 
was  kept  well  stirred  by  means  of  a  wooden  paddle.     When  2  cwt.  had  been 

1  This  paper  and  Abel's  later  one  on  the  Stability  of  Gun-cotton  (Trans.  Hoy.  Soc, 
1867,  p.  181)  are  out  of  print  and  not  always  accessible,  but  they  have  been  translated 
into  German  by  Dr.  B.  Pleuss  and   published   by  Fricdlanck-r,   Berlin,    1007. 

2  J.  Soc.  Chem.  Ind.,   1909,  p.    180. 


170  EXPLOSIVES 

immersed,  the  inflow  of  water  was  Btopped  and  the  tank  drained  down. 
When  all  the  water  had  been  run  oft'  the  tank  was  filled  up  again  with 
fresh  water.  This  was  repeated  six  times,  or  until  the  gun-cotton  no 
longer  tasted  acid.  When  this  stage  had  been  reached  the  gun-cotton 
was  wrung  in  a  centrifugal  machine,  water  from  a  hose-pipe  being  turned  on 
the  gun-cotton  for  one  minute  during  the  wringing,  and  it  was  then  ready 
for  boiling. 

"This  process,  although  it  undoubtedly  produced  a  good  gun-cotton, 
had  certain  disadvantages,  and  the  amount  of  labour  required  was  very  great. 
The  plant,  although  individual  items  were  not  expensive,  very  rapidly  deteri- 
orated, and  the  cost  of  renewals  and  replacements  was  heavy.  Power  was 
required  to  drive  the  centrifugal  machines,  large  quantities  of  water  were 
used  both  for  cooling  and  immersing,  and  decompositions,  in  the  pans,  pots, 
and  acid  centrifugals,  were  by  no  means  infrequent." 

In  order  to  save  the  laborious  and  unpleasant  operations  of  transporting 
the  nitrating  pots  from  the  dipping  pans  to  the  cooling  pits  and  from, there 
to  the  acid  centrifugals,  and  the  transfer  of  the  acid  and  cotton  from  one 
vessel  to  another  a  method  has  been  adopted,  especially  in  Germany,  of  nitrat- 
ing in  the  centrifugal  itself.  A  centrifugal  machine  used  in  this  way  lasts 
much  longer  than  might  be  expected,  for  several  years  in  fact  with  only  occa- 
sional repairs.  The  firm  which  has  had  the  widest  experience  in  building 
this  plant,  Selwig  and  Lange,  of  Brunswick,  has  introduced  several  improve- 
ments in  it.  The  basket  of  the  centrifugal  is  fitted  with  a  secondary  driving 
gear,  which  can  cause  it  to  rotate  slowly  during  the  period  of  nitration,  thus 
making  the  acids  circulate,  and  their  temperature  can  be  kept  at  any  desired 
point  by  means  of  a  water  jacket. 

The  nitrating  centrifugal  is  not  very  suitable  for  making  gun-cotton  of 
low  solubility  in  ether-alcohol,  because  unless  the  cotton  used  is  of  good  quality, 
parts  of  it  will  not  be  completely  nitrated  in  the  short  time  that  it  remains  in 
contact  with  the  acid. 

The  method  of  working  is  as  follows  :  First,  the  acid  is  run  into  the  centri- 
fugal by  turning  on  the  cock  on  the  pipe  communicating  with  the  supply  tank. 
Then  the  cotton  is  immersed  in  the  acid  a  little  at  a  time  until  there  is  about 
1  part  of  cotton  to  50  of  acid.  The  lid  is  then  shut  down  and  the  nitration 
is  allowed  to  jjroceed,  usually  for  a  quarter  to  three-quarters  of  an  hour,  accord- 
ing to  the  sort  of  nitro-cotton  that  is  being  made.  Then  the  acid  is  allowed 
to  drain  away  by  a  cock  communicating  with  the  waste-acid  tank.  The 
centrifugal  is  then  rotated,  slowly  at  first  and  gradually  more  rapidly  until 
the  proportion  of  free  acid  in  the  cotton  has  been  sufficiently  reduced. 
When  making  insoluble  gun-cotton  by  this  process  it  is  generally  desirable 
to  leave  not  less  than  1|  parts  of  free  acid  to  every  part  of  gun-cotton,  because 
if  the  wringing  be  carried  further  there  is  danger  of  the  charge  fuming  off,  or 


MANUFACTURE   OF  NITROCELLULOSE  171 

even  exploding.1     With  nitro-cotton  of  lower  nitration  the  wringing  can  be 
carried  somewhat  further. 

When  the  centrifugal  has  been  stopped  the  nitro-cotton  is  taken  out  by 
means  of  tongs  made  of  iron  or  aluminium,  and  removed  to  tanks  where  it  is 
immersed  in  running  water.  Selwig  and  Lange  have  introduced  an  auto- 
matic hydraulic  conveyor,  the  entrance  to  which  is  just  by  the  centrifugal 
and  may  be  seen  at  the  back  of  Fig.  31.  A  ring  of  water  jets  directed  down- 
wards just  below  the  opening  immediately  immerses  the  nitro-cotton  as  it  is 
introduced,  and  the  stream  of  water  carries  it  along  to  a  tank  where  the  washing 
with  cold  water  is  completed.  The  somewhat  dangerous  operation  of  carrying 
the  acid  cotton  in  wooden  boxes  or  other  receptacles  is  thus  avoided,  and 
there  is  also  a  saving  of  labour. 

During  the  operations  of  introducing  the  cotton  into  the  acid  and  of  remov- 
ing the  acid  cotton  after  nitration,  a  considerable  amount  of  acid  fume  is  given 
off,  and  it  is  therefore  necessary  to  provide  the  machine  with  a  draught  to 
draw  the  fumes  away.  Provision  for  doing  this  is  shown  on  the  left  side  of 
Fig.  31,  where  an  upright  earthenware  pipe  may  be  seen  communicating  witli 
the  interior  of  the  centrifugal.  This  is  intended  to  be  connected  by  means 
of  earthenware  pipes  with  a  stone-ware  fan.  I  have  found,  however,  that 
the  draught  produced  in  this  way  was  very  inadequate,  and  that  the  men 
who  did  the  nitrating  suffered  much  from  the  fumes  which  were  not  drawn 
away.  A  better  arrangement  was  to  make  the  lid  of  the  centrifugal  open  to 
one  side,  and  run  a  wooden  shaft  about  18  inches  square  along  the  back  of 
the  row  of  centrifugal  machines  with  an  opening  just  by  each  machine  that 
could  be  closed  with  an  aluminium  door.  At  the  other  end  of  the  wooden 
shaft  there  was  an  ordinary  propeller  fan  with  aluminium  blades  driven  from 
a  shaft.  This  created  a  much  better  draught  with  a  smaller  expenditure  of 
power,  and  the  cost  of  the  arrangement  was  much  less  than  that  of  the  stone- 
ware fan,  etc.  The  woodwork  had  to  be  renewed  from  time  to  time,  but  this 
was  far  less  expensive  than  the  repairs  to  the  stone- ware  fan  had  been. 

Information  about  the  various  types  of  nitrating  centrifugals  will  be  found 
in  a  paper  by  Grundlich.2 

At  Nobel's  factory  at  Ardeer  a  method  was  adopted  known  as  "  direct  Direct  dip] 
dipping."     According  to  a  communication  by  Mr.  Lundholm  to  Sir  F.  L. 
Nathan  the  process  was  as  follows  : 

"  The  installation  consists  of  parallel  double  rows  of  long  iron  tanks  known 
as  '  coolers.'     Iron  pots,  termed  *  dippers."  in  which  nitration  is  carried  out 

1  At  the  K.  B.  Pulverfabrik  at  Ingolstadt  the  contents  of  a  nitrating  centrifugal 
exploded  on  July  1,  1911,  killing  one  man  and  injuring  another.  The  machine  was 
being  emptied  at  the  time.  It  is  supposed  that  it  had  been  spun  too  long.  As  a  rule 
the  contents  merely  fume  off.     [S.S.,   1912,  p.   60.) 

2  S.S.,   1910,  Nob.  18,  21,  22,  23,  24. 


IM 


EXPLOSIVES 


stand  in  the  coolers,  Bixty-two  to  each  cooler.     Sliding  w ien  covers  resi 

on  the  coolers  to  guide  the  fames  from  the  dippers  into  earthen  ware  j>i]>e> 
with  openings  at  intervals,  through  which  they  are  drawn  by  exhaust  fans. 


Fio.  31.     Nitrating  Centrifugal  with  Hydraulic  Conveyor  for  tlie  Nitro-cottou 

Si  Iwig  and   Lang 

The  mixed  acid,  either  cooled  or  wanned  as  Decessary,  is  carried  by  lead  pipes 
placed  between  each  row  of  coolers,  and  i-  supplied  to  the  dippers  through 
earthenware  cocks  at  intervals. 

"Nitration.     The  water  in  the  coolers  is  kept   at    15    C.     The  dippers, 
having  been  placed  in  position  in  the  coolers,  are  each  filled  with  127  11..  of 


MANUFACTURE   OF  NITROCELLULOSE  173 

mixed  acid  by  measurement  from  the  acid  taps  ;  4|  lb.  of  cotton  waste  are 
steeped  in  each  dipper.  To  minimize  decompositions  each  charge  of  cotton 
waste  is  added  in  about  ten  instalments.  The  wooden  covers  are  only  removed 
to  allow  steeping  to  be  done,  and  are  then  at  once  replaced.  The  tempera- 
tures of  nitration  are  :  Initial  temperature  of  mixed  acid,  15°  C.  ;  maximum 
after  steeping,  25°  C.  ;  temperature  at  end  of  nitration,  20°  C.  The  duration 
of  the  nitration  varies  according  to  the  output  required  from  the  plant.  One, 
two.  or  three  shifts  may  be  worked  per  twenty-four  hours,  and  the  time  of 
nitration  may  therefore  be  twenty-four,  twelve,  or  eight  hours  respectively. 

i;  The  average  composition  of  the  mixed  acid  for  a  twelve  hours'  immersion 
is  as  follows  :  Sulphuric  acid,  75*0  per  cent.  ;  nitric  acid.  15-75  per  cent.  ; 
nitrous  acid.  1-30  per  cent.  ;  water.  7-95  per  cent.  For  an  eight  hours'  immer- 
sion a  higher  percentage  of  nitric  acid  and  less  water  is  used  ;  for  a  twenty- 
four  hours'  immersion  less  nitric  and  more  water.  The  average  composition 
of  the  waste  acid  for  a  twelve  hours'  immersion  is  :  Sulphuric  acid,  77-8  per 
cent.  ;  nitric  acid,  11-0  per  cent.  ;  nitrous  acid,  1-5  per  cent.  ;  water,  9-7 
per  cent. 

"  Recovering  the  waste  acid.  When  the  nitration  is  complete,  the  '  dippers,' 
covered  with  light  aluminium  lids,  are  placed  on  barrows,  wheeled  to  the  cen- 
trifugals situated  at  the  end  of  the  '  coolers,'  and  the  whole  contents  tilted 
out  into  the  centrifugals.  Four  dippers  are  loaded  into  each  centrifugal, 
and  the  gun-cotton  having  been  uniformly  spread  round  the  basket,  the  centri- 
fugal is  run  for  six  minutes  to  remove  waste  acid.  At  the  end  of  that  time 
about  1  lb.  of  waste  acid  is  still  adhering  to  each  pound  of  gun-cotton.  The 
centrifugal  cover,  made  of  light  aluminium,  is  not  fixed  to  the  centrifugal 
in  any  way,  so  that  as  little  resistance  as  possible  may  be  offered  when  there 
is  a  decomposition.  This  is  the  usual  arrangement  in  the  case  of  acid  centri- 
fugals. The  cone  of  the  centrifugal  projects  through  a  circular  opening  in  the 
centre  of  the  lid  and  is  covered  by  a  small  loose  aluminium  box.  Small  holes 
are  cut  in  the  sides  of  this  box,  and  are  of  service  in  warning  the  workmen 
when  there  is  a  decomposition,  as  fumes  are  generally  seen  to  issue  there  first. 

"Drowning  the  gun-cotton.  When  the  waste  acid  has  been  removed,  the 
gun-cotton  is  quickly  lifted  out  of  the  centrifugals  and  thrown  under  the 
revolving  paddles  of  the  drowning  tanks,  which  immediately  immerse  it. 
The  men  who  do  the  discharging  are  provided  with  rubber  gloves  and  wear 
thick  flannel  hoods,  which  completely  cover  the  head,  arms,  and  breast.  The 
hoods  are  fitted  with  strong  glass  windows,  and  are  connected  by  light  rubber 
tubing  to  a  supply  of  pure  compressed  air. 

"  Pit i-washii  g.  After  a  given  quantity  of  gun-cotton  has  been  drowned, 
the  water  in  the  tanks  is  run  off  and  the  gun-cotton  thrown  on  to  draining 
tallies  forming  part  of  the  drowning  tank.  It  is  then  loaded  into  the  pre- 
washing  centrifugals,  the  acid  water  wrung  out,  and  washed  for  a  few  minutes 


174 


EXPLOSIVES 


with  cold  water  from  a  hose  to  remove  adhering  acid.  Xo  special  precautions, 
however,  are  taken  to  remove  all  acid  at  thi>  >t;iLr<-.  The  bulk  of  the  water 
having  been  removed,  the  gun-cotton  is  Loaded  from  the  centrifugals  into 
bogie-  and  conveyed  to  the  boiling-hoi. 

'"  The  sixty-two  dippers  in  each  cooler  form  a  '  charge.'  Eight  charges 
are  worked  by  each  shift.  The  yield  i-  159  per  cent,  of  dry  gun-cotton  on 
the  dry-can  i>  >n.     The  output  per  >hift  consisting  of  seventeen  men  is 

therefore  :   4-5  X  159  X  62        -    '-  100  =  3549  lb. 


.  •  iii'-nt   Apparatus  (from  An 


"  Gun-cotton  has  been  made  at  Waltham  Abbey  by  Nathan  and  Thom- 

-  displacement  process  since  August   1905.     The  installation  consists  of  a 

number  <»f  units  of  four  pans  worked  together.     The  pans  are  of  earthenware  ' 

and  circular.  3  feet  •'»  inches  in  diameter,  and  1<»  inch-  t  the  side  of  the 

pan  ;  the  bottom  has  a  fall  <»f  2  indie-  to  the  outlet,  which  is  J-inch  in  diara 
They  are  supported  on  earthenware  pedestals  about  1  foot  10  inches  above 
the  floor  level.     The  four  pans  are  connected  together  by  lead  pipes,  and  these 
are  again  connected  to  the  nitrating  acid  supply  pipe,  t<>  the  strong  and  weak 
waste  acid  pipes,  and  to  a  waste  water  pipe,  through  a  Lr;niLrc-b<>.\.  where  the 

1  Pans  of  acid-resisting  iron  are  also  being  tried.     A.M..   1916, 


MANUFACTURE   OF   NITROCELLULOSE 


175 


rate  of  flow  is  determined  whilst  the  waste  acids  are  being  run  off.     Gravities 
of  the  acids  are  also  taken  in  this  box.     The  process  proceeds  as  follows  : 

"  A  small  perforated  plate  is  placed  over  the  outlet  of  each  pan,  and  four 


Fig.   33.     A  Unit  of  Four  Pans  (from  Arms  and  Explosives). 

perforated  segment  plates  making  a  complete  disc  about  1  inch  less  than  the 
inside  diameter  of  the  pan,  are  placed  on  the  bottom.  Aluminium  fume 
hoods,  which  are  connected  to  an  exhaust  fan,  having  been  placed  on  the  four 
pans,  the  stone-ware  cock  on  the  acid  sirpply  pipe  is  opened,  and  the  acid 


Fig.  34.     View  showing  Arrangement  of  Units  in  Rows  (from  Arms  and  Explosives). 

allowed  to  rise  in  the  pans  to  the  proper  level.  The  nitrating  acid  is  cooled 
in  summer  and  warmed  in  winter,  so  as  to  maintain  the  same  temperature 
of  final  nitration  all  the  year  round.  The  composition  of  the  nitrating  acid 
is  70-5  per  cent,  sulphuric  acid,  21  per  cent,  nitric  acid,  0-6  per  cent,  nitrous 


170 


EXPLOSIVES 


acid,  and  7-9  per  cent,  water:  the  quantity  in  each  pan  above  the  bottom 
]»lat-  ~  -  0  lb.,  and  below  the  plates  i>  an  additional  r>"  lb.  A  charge  of 
2<>  lb.  of  cotton  waste  is  then  immersed  in  the  acid,  handful  by  handful,  alu- 
minium  dipping-forks  being  used  for  the  purpose.  When  all  the  cotton  waste 
has  been  pushed  under  the  surface  of  the  acid,  perforated  plates  in  segments 
placed  on  the  top  of  it.  care  being  taken  that  all  cotton  waste  is  below 


Plumbing  Installation  for  Displacement  Plant    from  Ann*  and  Explosives). 


the  surface  of  the  acid,  and  a  film  of  water  at  a  temperature  from  5    <  .  to  v 
i-  run  very  gradually  on  the  surface  of  the  plates  through  a  distributor.     The 
film  of  water  prevent-  the  escape  of  acid  fumes,  and  the  fume  hoods  are  then 
removed.     The  time  required  for  dipping  a  charge  is  a  quarter  of  an  hour. 

**  The  nitration  is  allowed  to  proceed  for  two  and  a  half  hours.  At  the 
expiration  of  thi>  period  the  cork  leading  t<>  (he  gauge-box  is  opened,  and 
the  waste  arid  allowed  to  run  off  at  the  rate  of  about  IT  lb.  a  minute.  Water, 
cooled,  if  necessary,  is  run  on  the  top  of  the  perforated  plates,  through  the 


MANUFACTURE   OF   NITROCELLULOSE 


177 


distributor,  at  an  equivalent  rate.  The  major  portion,  ariiounting  to  about 
80  per  cent,  of  the  total  waste  acid,  is  returned  to  the  acid  store  tanks  to  be 
revivified  with  Nordhausen  sulphuric  and  new  nitric  acids.  The  composition 
of  this  waste  acid  is  72-70  per  cent,  sulphuric  acid,  17-30  per  cent,  nitric  acid, 
0-65  per  cent,  nitrous  acid,  and  9-35  per  cent,  water.  The  remaining  20  per 
cent,  of  the  waste  acid  is  sent  to  the  acid  concentration  factory  for  denitration 
and  concentration.  The  quantity  of  acid  thus  dealt  with  amounts  to  about 
4  lb.  for  every  pound  of  gun-cotton.  Its  composition  is  6 10  per  cent,  sul- 
phuric acid,  17-35  per  cent,  nitric  acid,  0-55  per  cent,  nitrous  acid,  and  21  10 
per  cent,  water.  A  small  proportion  of  the  water  which  follows  the  recover- 
able waste  acid  is  slightly  acid  to  the  extent  of  0-1  lb.  for  every  pound  of  gun- 
cotton  made.  This  is  the  total  quantity  of  acid  that  is  lost  during  the  process. 
In  the  direct  dipping  and  nitrating  centrifugal  processes  the  quantity  of  waste 
acid  left  in  the  gun-cotton  is  at  least  equal  to  the  weight  of  the  gun-cotton. 

"  The  whole  of  the  acid  is  displaced  in  three  hours,  and  the  water,  which 
should  fill  the  pan,  is  run  through  the  gun-cotton,  the  gun-cotton  drained 
down  and  sent  over  to  be  boiled.     These  operations  occupy  about  an  hour." 

The  following  Table  gives  the  principal  figures  in  connexion  with  the  four 
nitration  processes  described  : 


Walt  ham 

Ardeer 

Dartford 

Waltham 

Process 

Abbey 

direct 

nitrating 

Abbey 

Abel 

dipping 

centrifugal 

displacement 

Acids,  Analysis  : 

H2S04 

740 

75-0 

69-35 

70-5 

HN03 

18-0 

15-75 

2315 

210 

HN02 

0-6 

1-3 

— 

0-6 

H20  ". 

7-4 

7-95 

7-5 

7-9 

Quantity,  lbs. 

13-75 

127 

800-1 100 

650 

Cotton  waste,  lbs. 

H 

±h 

16-24 

20 

Acid  per  lb.  cotton  . 

110 

28-2 

50-0 

32-5 

Time  of  nitration,  hours    . 

12 

12 

1 

2| 

Yield  on  dry  cotton,    %     . 

164 

159 

160 

170 

Output  per  man  per  week,  lb.  . 

458 

1112 

(3000) 

1742 

Note. — The  output  with  nitrating  centrifugals  is  not  given  in  the  original  paper.  It 
is  approximately  as  stated. 

The  following  are  the  principal  advantages  which  the  displacement  process 
possesses  over  the  Abel  process,  and  over  the  direct  dipping  and  nitrating 
centrifugal  processes  where  they  are  similar  to  the  Abel  process  : 

(1)  The  displacement  process  takes  the  place  of  the  processes  of  dipping, 
squeezing  out  excess  acid,  digesting  in  pots,  acid  centrifugaling,  immersing, 
and  water  centrifugaling. 

VOL.   I.  12 


178  EXPLOSIVES 

i  2)  The  actual  clipping  of  the  cotton  waste  is  a  very  much  less  laborious 
operation — the  heavy  labour  of  squeezing  out  the  excess  acid  is  done  away 
with  ;  the  absence  of  fumes  makes  the  work  much  healthier,  and  injuries  to 
workmen  from  acid  splashes  are  almost  unknown. 

(3)  Loss  of  gun-cotton  due  to  decomposition  in  the  digesting  pots  and 
acid  centrifugals,  and  consequent  inconvenience  and  danger  to  workmen 
from  nitrous  fumes,  are  done  away  with,  and  the  heavy  Loss  from  breal 

of  pots  and  lids  is  saved.     Three  and  a  half  years'  experience  has  proved  that 
the  earthenware  pans  are  very  lasting. 

(4)  Fumes  during  dipping,  loading,  and  unloading  acid  centrifugals  and 
immersing,  arc  avoided. 

(5)  The  quantity  of  acid  lost  is  very  much  reduced.  This  reduction 
means  also   very  much  less  pollution  of  the  escaping  washing  water. 

(6)  The  recovered  waste  acid  is  very  much  cleaner,  a  matter  of  the  great- 
est  importance  from  the  point  of  view  of  revivification  and  concentration. 

(7)  The  mechanical  loss  of  gun-cotton  in  the  acid  and  water  centrifugaling 
processes,  and  in  the  immersing  process,  is  saved. 

(8)  A  more  thorough  preliminary  washing  of  the  gun-cotton  is  obtained 
with  an  expenditure  of  about  one-fifth  of  the  quantity  of  water,  and  less 
boiling,  and  consequently  less  steam,  is  required  in  order  to  reach  a  given 
standard  of  purity. 

(9)  Civat  saving  in  power  is  gained  by  the  abolition  of  the  acid  and  water 
centrifugals,  and  by  the  reduction  in  the  quantity  of  water  which  has  to  be 
pumped. 

(10)  Renewals  of  plant,  and  repairs  to  plant  and  buildings  are  exceedingly 
low. 

(11)  The  number  of  hands  employed  for  any  given  output  is  much  less — 
the  total  cost  of  labour  being  reduced  by  two-thirds. 

(12)  The  yield  is  improved;  it  averages  170  per  cent. 

(13)  Finally,  a  more  stable  gun-cotton,  of  more  uniform  composition,  is 
produced.     It  is  also  far  cleaner  and  contains  notably  less  mineral  matter. 

The  last  claim  especially  has  proved  to  be  amply  justified.  Cordite  made 
from  gun-cotton  manufactured  by  the  displacement  process  >h<>\\s  promise 
of  lasting  about  twice  as  long  under  adverse  climatic  conditions,  a-  that  in 
which  the  Abel  process  was  used,  in  spite  of  the  fact  that  the  latter  would 
compare  favourably  with  any  other  gun-cotton  made  except  by  the  displace- 
ment process. 

This  improved  stability  is  probably  connected  with  a  curious  fact  which 

has    been    observed   by    .Ma.  Donald.1     He   found    that    as    the    displacement 

proceed.,  the  percentage  of  nitric  acid  in  the  waste  arid  after  falling  slightly 

has  a  distinct  rise  and  then  falls  again  (.sec  Fig.  36).     The  ratio  of  nitric  to 

1  J.  Soc.  Chan,  li»i..   1911,  p.  251. 


MANUFACTURE   OF  NITROCELLULOSE 


179 


sulphuric  acid  also,  after  a  very  slight  fall,  rises  steadily  until  the  end  of  the 
displacement  and  washing.  This  can  only  be  due  to  a  partial  denitration  of 
the  gun-cotton,  and  evidently  the  more  unstable  products  are  decomposed 
to  a  greater  extent  than  the  normal  stable  gun-cotton. 

The  recovery  of  the  waste  acid  is  far  more  complete  than  by  any  other 
process,  but,  on  the  other  hand,  it  is  diluted  somewhat  with  the  water  used 
for   the   displacement.     Consequently   a   considerable  plant   is   required   for 


j 

r 

t 

f 

/ 

/ 

/ 

1    ■ 

" 

1 

OC- 

h 

h 

'1' 

J> 

1 

! 

i 

I 

M 

H 

e 

( 

d°           =  — 

^ 

W     10 

.7 


.6 


.5 


PC 


10 


40 


50 


20  30 

Time   in  Minutes 
Fig.  36.     Composition  of  Displaced  Acids. 

working  up  the  acids  again  and  reconcent rating  them.  According  to  Mac- 
Donald  the  loss  of  acid  is  only  008  lb.  per  pound  of  gun-cotton  produced, 
but  his  own  figures,  as  has  been  pointed  out  by  Delpy,1  indicate  a  very  much 
higher  loss. 

In  all  the  processes  except  that  of  displacement  there  is  liability  of  the 
charge  fuming  off  either  in  the  pots  or  centrifugals.  This  is  especially  the 
case  in  hot  weather  or  if  the  cotton  has  not  been  sufficiently  purified  from 
grease,  etc.,  or  has  hard  Lumps  in  it  which  the  acids  can  only  penetrate  slowly. 

According  to  Wbrden,2  tissue  paper  for  lacquers  is  nitrated  in  America  Hyatt niti 
in  pots,  which  are  placed  on  a  rotating  table,  about  which  are  arranged  inlets 
1  S.S.,   1912,  p.  237,  -   Xiirc-ceUukfi  Industry,  p.   110, 


180  EXPLOSIVES 

for  acid,  a  starring  apparatus,  and  a  mechanism  for  tipping  the  pots  into  a 
centrifugal.  The  plant  must  he  somewhat  cumbersome  and  expensive,  and 
is  not  likely  to  be  adopted  for  the  manufacture  of  explosives. 
High  nitrogen  The  details  given  by  Sir  F.  L.  Nathan  refer  to  the  manufacture  of  gun- 
cotton  containing  about  13  per  rent.  X.  If  it  be  desired  to  obtain  a  product 
with  a  higher  percentage  of  nitrogen,  it  is  necessary  t<»  increase  the  proportion 
.»f  nitric  arid  in  the  mixed  acid  (so  Pigs.  28,  29),  hut  it  i-  not  very  often  that 
it  is  required  to  obtain  a  percentage  much  higher  than  13,  because  such 
products  ait.-  Less  stable  and  art-  more  expensive  t<>  manufacture.  It  has 
been  shown  by  Lunge  and  Bebie  that  beyond  13-5  per  cent,  the  products  are 
quite  unstable  (see  p.   136). 

For  tlie  manufacture  of  various  smokeless  powders  nitro-cottons  partially 
soluble  in  ether-alcohol  are  used.  The  acid  mixture  to  be  employed  depends 
upon  the  sort  of  cellulose  and  the  method  of  nitration. 

For  a  nitro-cotton  totally  soluble  in  ether-alcohol  there  should,  according 
to  Pig.  29,  be  a  molecule  of  water  for  every  molecule  of  acid,  whether  nitric 
or  sulphuric,  but  in  practical  manufacture  a  smaller  proportion  of  water  i- 
generally  used,  especially  if  a  high  percentage  of  nitrogen  is  required.  At 
one  time  it  was  thought  to  be  impossible  to  prepare  a  totally  soluble  product 
containing  more  than  12  per  cent.  X.  Mendeleefl,  however,  who  worked 
at  this  subject  from  1891  to  about  1895,  produced  a  soluble  nitro-cotton  with 
about  12-5  per  cent.  X.  and  he  pointed  out  that  a  product  with  12-44  per  cent, 
contains  just  enough  oxygen  to  convert  all  the  carbon  into  CO  and  all  the 
hydrogen  into  water.  This  material,  which  has  been  called  pyro-coUodion, 
was  adopted  as  the  basis  of  the  Russian  military  smokeless  powder,  and  later 
the  United  State-  adopted  a  powder  made  from  a  pyro-collodion  containing 
about  12-.")  to  12-7  per  cent.  X.  This  is  produced  by  nitrating  at  a  compara- 
tively high  temperature.  According  to  Worden.1  in  Picatinny  Arsenal  the 
nitration  is  now  carried  out  in  Thomson's  displacement  plant.  The  acid  has 
the  composition  : 

By  weight  Molecular 

UNO,         .  .  .  .21   22  ..  18-7 

H2S04         ....     63-64  .  .  36-3 

H;0 15  ..  46-2 

The  temperature  is  30°-32  .  and  the  charge  in  each  pan  consists  of  20  lb. 
cotton  and   Too  ll>.  acid. 

A  high  degree  of  nitration  la  also  desirable  for  the  collodion  used  for  the 
manufacture  of  blasting  gelatine  and  other  similar  high  explosives,  but  the 
uitro-glycerine  contains  an  excess  of  oxygen,  and  the  proportion  of  collodion 
cotton  is  small,  bo  that  high  power  is  not  of  the  same  importance  as  in  the  case 
of  a  military  powder.     The  greal  essentia]  is  that  the  collodion  cotton  shall 

1  Nitrxhcettuloae  Industry,  p.  97, 


MANUFACTURE   OF   NITROCELLULOSE  181 

give  a  good  stiff  colloid  with  the  nitro-glycerine.  Other  things  being  equal 
a  cotton  of  high  nitrogen  will  give  a  stiffer  gelatine  than  one  of  low,  but  it 
will  dissolve  more  slowly,  with  the  result  that  the  material  will  become  stiffer 
on  prolonged  storage  and  less  sensitive,  and  this  may  cause  missfires.  The 
percentage  of  nitrogen  in  collodion  cotton  for  blasting  explosives  is  usually 
between  11-5  and  12  per  cent.  The  official  definition  of  H.M.  Inspectors  of 
Explosives  gives  an  upper  limit  of  12  3  per  cent.  It  is  of  great  importance 
that  the  cotton  before  nitration  shall  not  be  submitted  to  drastic  treatment 
either  with  chemicals  or  heat,  for  this  breaks  down  the  molecules  of  cellulose 
and  makes  the  blasting  gelatine  soft.  For  the  same  reason  the  nitrated 
product  is  not  boiled,  as  is  done  in  the  case  of  gun-cotton,  but  it  is  treated 
for  some  days  with  water  at  a  temperature  of  about  90°.  The  pulping  also 
is  not  carried  so  far. 

For  the  manufacture  of  artificial  silk  and  lacquers,  etc.,  a  collodion  is  Coiiodic 
required  that  shall  be  as  little  viscous  as  possible,  so  that  only  a  comparatively  jjjj  ^J 
small  proportion  of  solvent  is  required.  A  high  degree  of  nitration  is  objec- 
tionable. Consequently  the  process  of  manufacture  differs  in  many  respects 
from  that  of  collodion  for  blasting  gelatine.  The  nitration  may  be  carried 
out  at  a  high  temperature,  40°  say,  for  several  hours  with  a  mixed  acid  con- 
taining about  18  per  cent,  water  and  about  20  per  cent,  nitric  acid.1  For 
other  purposes,  such  as  the  preparation  of  collodion  solution  for  dipping 
incandescent  mantles,  a  collodion  of  intermediate  viscosity  is  required. 

1  See  T.  Chandelon,  Bui  Soc.  Chim.  Belg.,  1914,  28,  pp.   13,  24. 


CHAPTER   XIII 

THE   STABILIZATION  OF  NITRO-CELLULOSE 

Early  methods  :  Boiling  :  Pulping  :  Removal  of  foreign  bodies  :  Poaching  : 
Blending  :  Addition  of  calcium  carbonate  :  Moulding,  etc.  :  The  beater  : 
Alkaline  method   of   stabilization  :  Sulphnrj  -   :   Velocity  of  hydrolysis 

of  nitro-celluloae  :   U.S.   Ordnance  method  :  Cellulose   nitrites  :  Products  of 

shing  collodion  cotton 

The  gun-cotton  that  was  manufactured  in  the  early  day-  was  purified  by 
washing  in  cold  water  only,  and  it  i-  principally  to  this  very  inadequate 
treatment  that  the  numerous  catastrophes  of  those  times  are  to  be  ascribed. 
One  of  von  Lenk-  most  important  improvements  was  the  introduction  of  a 
boiling  of  fifteen  minutes  with  a  potash  solution  ific  gravity  1-02.     Sir 

F.  Abel  tried  pulping  the  gun-cotton  with  the  object  of  obtaining  it  in  a  more 
compact  and  convenient  form.  In  his  patent  specification,  No.  L102  of  L865, 
he  say-  : 

Now  my  invention  has  for  its  object  to  assimilate  the  physical  condition 
of  gun-cotton  a<  nearly  as  possible  to  that  of  gunpowder  by  mechanically 
converting  it  into  a  solid  conglomerate  and  imparting  to  it  either  a 

granular  or  other  suitable  form  that  will  present  the  exact  amount  of  surface 
and  compactness  required  for  obtaining  a  certain  rapidity  or  intensity  of 
combustion. 

':  I  first  convert  cotton  wool  by  tin-  processes  now  well  known  into  gun- 
cotton.  For  this  purpose  I  prefer  to  use  the  cotton  in  the  form  of  a  loose 
roving.  When  the  gun-cotton  has  been  purified  from  acid  by  washing  in 
running  water  and  in  very  dilute  alkali.  I  transfer  it  to  a  beating  engine  of 
the  description  commonly  used  in  the  manufacture  of  paper,  where  it  is  reduced 
to  a  pulp,  which  Lb  then  converted  into  Bolid  masses    .  . 

Prolonged  boiling  with  water,  which  is  an  essential  feature  of  the  modern 
proce>s  of  stabilization,  was  not  introduced  until  considerably  later,  sir 
F.  L.  Nathan  remark-  '  that  :  "  1  i <  •  i I i 1 1 lt  as  now  understood  did  not  form  part 
of  the  process  of  gun-cotton  manufacture  when  manufacture  was  started  at 
Walt  ham  Abbey  early  in  1872.  Aboul  the  middle  of  1873,  however,  boiling 
1  J .&  <    p.  L80. 


THE   STABILIZATION   OF  NITRO-CELLULOSE 


183 


vats  were  put  up  at  Waltham  Abbey,  but  no  records  exist,  unfortunately, 
about  the  details  of  the  early  boiling  processes.  In  the  official  Notes  on  Gun- 
powder and  Chin-cotton,  published  by  the  War  Office  in  1878,  it  is  stated  that 
gun-cotton  manufactured  at  Waltham  Abbey  underwent  two  boilings  by 
steam  in  wooden  vats  for  eight  hours  each,  the  water  being  extracted  after 
each  boiling  by  wringing  for  three  minutes  in  clean  water  centrifugal  machines. 
The  same  boiling  process  was  in  use  in  1888,  according  to  a  later  edition  of  the 
same  book.  Five  years  later  each  boiling  was  extended  to  twelve  hours, 
and  the  boiling  lasted  for  five  days  and  nights — that  is,  the  gun-cotton  received 
ten  boilings  of  twelve  hours  each.  In  April  1894,  this  system  of  boiling  was 
replaced  by  a  system  characterized  by  short  boilings  at  the  commencement 
of  the  process,  the  time  of  successive  boilings  being  gradually  increased.  The 
scheme  of  boiling  was  as  follows  : 


No.  of  boiling 

Duration  in  hours 

No.  of  boiling 

Duration  in  hours 

1 

2 

7 

(i 

2 

2 

8 

6 

3 

4 

9 

9 

4 

4 

10 

9 

5 

6 

11 

12 

6 

6 

12 

12 

"  This  system  of  boiling  was  continued  with  but  slight  modifications  until 
August  1905.  On  the  introduction  of  the  displacement  dipping  process  it 
was  found,  as  already  stated,  that  gun-cotton  made  in  this  way  was  brought 
to  a  condition  of  stability  by  the  boiling  process  then  in  Use,  and  just  referred 
to,  at  an  earlier  stage  than  gun-cotton  made  by  the  Abel  process.  A  probable 
explanation  of  this  fact  is  that  during  the  displacement  process  a  zone  of 
acid  liquid  at  a  comparatively  high  temperature— somewhere  about  40°  C- — 
passes  through  the  whole  of  the  gun-cotton  in  the  cupping  pan.  The  action 
of  this  hot  acid  liquid  may  be  to  oxidize  certain  organic  impurities  which  are 
certainly  present,  and  to  cause  the  breaking  down  of  unstable  nitrogen  com- 
pounds into  soluble  or  non-reactive  bodies.  Systematic  experiments  were 
therefore  carried  out,  in  1905,  to  determine  the  most  suitable  and  most  econo- 
mical method  ol  purification  by  boiling  for  displacement  process  gun-cotton. 
In  the  principal  experiments  two  types  of  boiling  were  employed — one  in  which 
long  boilings  were  used  at  first,  followed  by  short  boilings  ;  the  otheran  which 
short  boilings  were  used  at  first,  followed  by  long  boilings.  The  following 
deductions  were  made  from  the  results  obtained  in  these  experiments: 

"  (1)  Purification  of  gun-cotton  obtained  by  means   of  long  boilings  at 
the  beginning  followed  by  shorter  boilings  later,  is  superior  to  that  obtained 


1S4 


EXPLOSIVES 


when  the  reverse  condition  holds.  Thi>  is  substantiated  by  the  following 
considerations  :  Examination  of  the  water-  showed  that  neutrality  is  obtained 
earlier  :  that  less  decomposition  of  the  gun-cotton  takes  place  :  that  the 
stability,  as  shown  by  the  various  stability  tests,  is  greater  ;  and  that  a  stable 
condition  is  attained  earlier. 

'"  (2)  A  displacement  washing  after  a  long  acid  boiling  at  an  early  stage 
is  a  beneficial  treatment.1  This  treatment  is  probably  responsible  for  the 
early  attainment   of  neutrality. 

'  The  system  of  boiling  determined  on  a-  a  result  of  these  experiments 
was  as  follows  : 


X<«.  of  boiling 

Duration  in  hours 

No.  of  1  ><  •  i  1  i  1 1  i_r 

Duration  in  hours 

1 

12 

6 

4 

2 

12 

7 

4 

3 

4 

8 

2 

4 

4 

9 

2 

5 

4 

10 

2 

with  a  cold  water  displacement  wash  after  the  first  two  boilings.  A  full 
account  of  these  investigations  was  given  by  Dr.  Robertson  in  a  paper  on 
the  purification  and  stabilization  of  gun-cotton.-  Thi>  system  of  boiling  is 
still  in  use  at  the  Royal  Gunpowder  Factory. 

"  The  question  of  how  the  purification  of  gun-cotton  can  best  be  et: 
cannot,  however,  be  considered  as  settled,  nor  can  the  system  which  has  just 
been  described,  although  it  undoubtedly  gives  an  excellent  gun-cotton  at  the 
Royal  Gunpowder  Factory,  be  applied  to  gun-cotton  made  by  other  prooi 
at  other  factories,  without  full  investigations  as  to  it-  suitability.  Another 
matter  which  must  be  taken  into  account  in  connexion  with  the  purification 
of  gun-cotton  by  boiling,  is  the  nature  of  the  water  available.  The  water 
at  Walt  ham  Abbey  i-  very  hard,  and  its  alkalinity  may  be  an  important 
factor  in  the  success  of  the  boiling  treatment  in  use  there.  This  question 
is  perhaps  connected  with  another  one.  and  that  is,  that  the  boiling  of  gun- 
cotton  can  be  carried  too  far.  The  effect  of  boiling,  whilst  it  no  doubt  breaks 
down  impurities,  also,  no  doubt,  breaks  down  the  -table  ester  itself.  It  is 
well  known  that  if  gun-cotton  is  boiled  for  a  sufficiently  prolonged  period, 
the  percentage  of  soluble  matter  will  rise  and  the  nitrogen-content  will  fall. 
The  breaking  down  of  ester  will  be  accompanied  by  the  formation  of  arid 

1  A  good  method  is  to  run  in  cold  water  at  th>-  bottom  of  the  vat,  which  remains 
full  of  water  the  whole  time.     The  contents  then  do  not  settle  down  to  a  compact  mass. 

2  J.  Soc.  Chew.   Ind..    1906,  p.   624 


THE  STABILIZATION   OF  NITROCELLULOSE  185 

bodies,  and  the  presence  of  alkali  in  the  water  will  neutralize  them  and  pre- 
vent them  from  reacting  on  the  gun-cotton." 

Since  the  above  was  written  it  has  been  found  possible  to  reduce  the  time 
of  boiling  still  further  without  affecting  injuriously  gun-cotton  made  by  the 
displacement  process. 

"  On  completion  of  the  boiling  process  the  gun-cotton  is  transferred  to  Pulping, 
a  beating  engine  somewhat  similar  to  that  employed  for  pulping  the  raw 
material  used  in  the  manufacture  of  paper.  It  consists  essentially  of  a  large 
iron  roller  armed  with  steel  knives,  and  a  bed-plate  also  provided  with  knives. 
The  roller  revolves,  and  as  the  gun-cotton  passes  between  the  two  sets  of 
knives,  it  is  reduced  to  pulp  of  any  desired  fineness.  As  the  pulping  process 
proceeds,  the  roller  is  gradually  lowered  nearer  to  the  bed-plate. 

"  Since  the  introduction  of  a  thorough  system  of  purification  by  boiling, 
Abel's  original  idea  that  the  pulping  and  washing  the  gun-cotton  received 
in  the  pulping  process  had  a  very  material  effect  on  its  purification,  no  longer 
holds  good  to  the  same  extent.  At  the  same  time  there  is  no  doubt  that  the 
very  long  staple  gun-cotton  before  pulping  retains  in  its  tubes  unstable  bodies 
which  no  reasonable  amount  of  boiling  will  remove.  The  effect  of  pulping 
is  to  reduce  materially  the  length  of  the  fibres  and.  at  the  same  time,  to  pro- 
duce a  certain  amount  of  crushing  in  them.  This  allows  of  impurities  of  an 
acid  character  in  the  tubes  being  removed,  either  mechanically  or  by  diffusion. 

"  After  pulping,  it  is  now  customary  to  treat  the  gun-cotton  in  some  Removal  i 
mechanical  way,  in  order  to  remove  from  it  particles  of  metal,  grit,  and  for-  fo^el&nbo, 
eign  bodies  of  a  similar  character.  At  the  Royal  Gunpowder  Factory  this 
is  effected  by  running  the  gun-cotton  pulp,  suspended  in  a  large  volume  of 
water,  through  grit  traps,  placed  at  intervals  in  a  long  shallow  trough,  the 
bottom  of  which  is  covered  with  blanket.  The  foreign  bodies,  being  almost 
entirely  heavier  than  the  gun-cotton  pulp,  are  retained  in  the  grit  traps,  and 
the  fine  sand,  also  present  in  some  quantity,  is  caught  by  the  woolly  blanket . 
An  electro  magnet  in  the  last  grit  trap  removes  any  magnetic  particles  passing 
the  ordinary  grit  traps.  It  is  surprising  what  a  large  quantity  of  foreign 
bodies  are  removed  by  these  arrangements.  In  addition  to  grit  traps  and 
troughs,  some  factories  use  what  is  known  as  a  knotter,  the  function  of  which 
is  to  remove  small  knots  and  any  large  pieces  of  gun-cotton  which  may  have 
escaped  complete  pulping. 

".Washing  the  gun-cotton  during  the  pulping  is  effected  in  some  factories  Poaching. 
by  the  use  of  drum  washers  fixed  to  the  beating  engine  .  in  the  Royal  Gun- 
powder Factory  and  other  factories  this  washing  is  done  in  separate  vessels 
termed  '  poachers.9  The  poachers  in  use  at  Waltham  Abbey  hold  about  1<> 
cwt.  of  gun-cotton  and  1100  gallons  of  water,  and  are  fitted  witli  power- 
driven  paddles  for  agitation  purposes.  The  gun-cotton  receives  at  least 
three  washings  ;    it  is  allowed  to  settle  down  after  each  washing,  and  the 


186 


EXPLOSIVES 


washing  water  is  removed  by  a  >kimmer.  The  washing  water  contain  in 
suspension  foreign  bodies  of  a  lower  specific  gravity  than  gun-cotton,  and  in 
the  case  of  the  earlier  washing  waters,  there  is  always  present  a  scum  con- 
taining nitro-bodiea  of  low  stability 

•■  A  further  purpose  served  by  poaching  is  the  thorough  blending  of  a 
number  oi  different  batches.  Tin-  is  a  final  blending,  but  at  the  Royal  Gun- 
powder Factory  there  exists  a  regular  system  of  blending  right  through  the 
whole  of  the  manufacturing  processee  This  system  is  briefly  as  follows: 
The  cotton  waste  reaches  the  factory  in  consignments  from  different  con- 
tractors.  The  waste  is  drawn  from  the  Btore  in  proportion  to  the  quantities 
on  the  contracts,  and  is  mixed  and  passed  through  the  teasing  machine  in 
these  proportions. 

''The  next  process  where  blending  is  possible  is  in  charging  the  boiling 
vats.  Two  vats  are  rilled  simultaneously  from  a  number  of  sets  of  pans — 
two  pans  of  each  set  of  four  going  into  one  vat  ;  the  other  two  of  the  set  into 
the  other  vat.  On  completion  of  the  boning,  four  vats  are  emptied  simulta- 
neously into  thirty-two  beaters.  This  ensures  the  gun-cotton  from  the  four 
vats  being  blended  together  in  the  beating  pro< 

"On  the  completion  of  the  pulping  the  beaters  are  run  alternately  into 
the  poachers  in  such  a  manner  that  the  contents  of  the  thirty-two  beater- 
are  blended  into  eight  poachers.  The  gun-cotton  in  the  eight  poachers  is 
therefore  uniform  throughout. 

"The  system  produces  gun-cotton  of  very  uniform  nitrogen-content. 
In  1907-1908,  291  tests,  representing  600  tons  of  gun-cotton,  gave  the  follow- 
ing nitrogen  result 


Maximum                                       Minimum 

Mean 

13-05                                            12-93 

Per  cent. 
13-0195 

Prom  the  poacher  the  pulp  passes  to  a  "  stuff-chest  "  or  large  tank  provided 
with  -tilling  arms.  About  this  Mam-,  if  the  gun-cotton  is  to  be  made  into 
compressed  blocks  for  blasting,  stabilizing  matter-  are  added,  usually  calcium 
carbonate.  If  the  water  used  be  hard  a  considerable  amount  may  be  precipi- 
tated on  the  fibres  by  the  addition  of  lime  water.  If  the  water  Ik-  soft,  or 
the  quantity  <»f  calcium  carbonate  to  be  added  In-  large-,  it  may  be  added  in 
the  form  of  whiting. 

To  remove  the  great  bulk  of  the  water  the  pulp  may  now  be  passed  into 
a  centrifugal  machine,  lined  with  fine  canvas.  The  dam])  ma>s  thus  obtained 
still  contains  40  or  50  per  cent,  of  water.      It  may  be  Bent  away  from  the  gun- 


THE   STABILIZATION   OF  NITRO-CELLULOSE  187 

cotton  factory  in  this  form,  or  it  may  be  moulded  first  into  blocks.  This  is 
done  by  loading  it  into  a  hydraulic  press,  where  it  is  subjected  to  a  pressure 
of  30  or  40  lb.  per  square  inch.  Presses  are  also  made  which  dispense  with 
the  preliminary  wringing  in  the  centrifugal  machine.  These  have  hollow 
plungers  covered  with  fine  wire  gauze,  and  the  bulk  of  the  water  is  drawn 
off  through  these  by  the  application  of  a  vacuum.  The  hydraulic  pressure 
is  then  applied  whereby  the  gun-cotton  is  moulded  into  a  block  or  cylinder, 
which  can  be  handled  conveniently. 

An  important  point  concerning  the  beating  engine  is  to  secure  a  very  The  beater 
good  circulation  of  the  water.     In  the  machines  used  in  the  paper  industry 


Fig.   37.     Beater  for  Pulping  Gun-cotton. 

the  rotation  of  the  drum  causes  the  water  to  move  round  so  fast  that  the 
fibrous  cellulose  material  cannot  settle,  but  is  carried  round  and  round,  so 
that  it  comes  repeatedly  under  the  knives,  until  it  has  been  reduced  to 'the 
required  degree  of  fineness,  and  the  machine  requires  very  little  attention 
But  if  the  same  machine  be  used  to  pulp  nitro-cotton,  it  is  found  that  the 
solid  material  tends  to  settle  down  at  the  bottom,  and  it  is  necessary  for  a 
man  to  attend  the  machine  and  help  the  material  round  with  a  wooden  paddle. 
This  is  not  due  entirely  to  the  increase  of  the  specific  gravity,  for  that  of 
nitro-cotton  is  only  1-67.  whilst  that  of  cotton  is  about  Mil.  but  in  the  nitra- 
tion the  weight  of  each  fibre  has  increased  about  70  per  cent.  The  length 
has  not  become  Greater,  probably  it  has  diminished  somewhat,  consequently 
each  fibre  has  become  much  stouter,  as  may  be  seen  clearly  on  comparing 
micro-photos  1  ami  7,  Fig.  30.     There  is  therefore  much  more  weight  for  the 


188 


EXPLOSIVES 


same  amount  of  surface,  and  consequently  the  materia]  is  borne  along  by 
the  water  with  greater  difficulty. 

A  good  form  of  beater  i<  that  of  Hoyt,  in  which  the  material  i-  made  to 
circulate  vertically  instead  of  horizontally.     Tin-  drum  carries  the  w 
pulp  right  over,  after  which  they  descend  a  steep  incline,  then  another  under 
this  sloping  in  the  opposite  direction  to  the  low*  st  point  of  the  knife  drum. 

The  fixed  knives  under  the  rotating  drum  require  to  be  sharpened  fre- 
quently, and  it  ifl  usual  to  have  a  duplicate  set.  The  knife-blades  on  the 
drum  also  require  sharpening  from  time  to  time.  They  thus  become  gradually 
shorter,  and  this  causes  the  circulation  of  the  pulp  to  become  won 

The  knives  are  sometimes  made  of  phosphoi  bronze,  as  it  has  been  found 
that  particles  of  iron  have  a  deleterious  effect  on  the  stability  of  the  nitro- 
cellulose,  but  they  have  the  disadvantage  that  they  wear  faster  than  - 
knives. 

The  development  of  the  method  of  stabilization  took  a  somewhat  different 
courx-  in  some  factories  ;  a  boiling  process  has  been  introduced,  after  the 
pulping,  and  was  carried  out  in  large  iron  tanks  fitted  with  stirring  gear  and 
valves  for  running  off  the  water  at  different  level-.  The  water  had  to  be 
kept  alkaline  throughout  the  operation-,  else  tin-  acid  developed  by  the  nitro- 
cotton  would  attack  the  iron  of  the  vessels.  At  fii-t  sight  it  appears  as  though 
the  boiling  in  the  pulped  state  must  purify  the  material  much  more  effectually 
than  when  the  material  i-  compact,  but  experience  has  proved  that  this  is 
not  so.  Robertson  has  shown  that  the  most  important  part  of  the  purification 
is  the  boiling  with  dilute  acid,  and  in  the  alkaline  method  this  is  omitted 
altogether.  Actual  tests  and  trials  have  shown  that  the  gun-cotton  stabilized 
by  this  process  is  distinctly  inferior  to  that  prepared  by  the  Waltham  Abbey 
process. 

The  reason  for  this,  or  at  least  one  reason,  was  revealed  by  the  observation 
of  Cross.  Bevan.  and  Jenks,  that  mixed  esters  containing  both  sulphuric  and 
nitric  acid  residues  are  liable  to  be  formed  when  cellulose  i-  immersed  in  the 
mixed  acids.1  The  observation  was  confirmed  by  Hake  and  Lewis.-  and 
was  further  investigated  by  Hake  and  Bell.3  When  these  products  are  all 
to  stand  they  gradually  become  acid  in  consequence  of  the  formation  of  free 
sulphuric  acid,  which  may  ultimately  Lead  to  the  spontaneous  explosion  of 
the  gun-cotton.  Hake  and  Lewi-  suggested  that  the  disastrous  expl 
at   Stowmarket  in   1871   was  probably  caused  by  the  presence  of  sulphuric 

It  was  shown  by  Robertson4  that  th<-  Bulphuric  esters  are  decon  | 
hvdrolytically  by  boiling  with  acid  water  much  more  rapidly  than  with  alkaline 


1  Ber..    1901,  p.  2491  '       ,  vol.  ii..  p.  51. 

2  J.  8oc.  Chem.  I  >■>!..   1905,  pp.  :;T4  and  '.'14. 

3  J.  8oc  Chem.   /,../..  1909,  p.  457. 


• ''  x  •  ■  -  ■ 


THE   STABILIZATION   OF  NITROCELLULOSE  189 

water  ;  in  fact  treatment  with  alkalis  seems  to  fix  the  sulphuric  group  firmly 
into  the  product.  This  behaviour  is  very  similar  to  that  of  the  cellulose 
aceto-sulphates,  which  have  been  investigated  by  Cross,  Bevan,  and  Briggs.1 
They  found  that  even  under  the  action  of  cold  distilled  water  the  sulphuric 
acid  residue  of  these  mixed  esters  was  gradually  split  off,  but  much  more 
rapidly  in  boiling  water,  w  lieieas  on  treatment  with  alkaline  solutions  the  whole 
of  the  acetic  acid  residue  could  be  eliminated  by  saponification,  whilst  the 
combination  between  the  cellulose  and  the  sulphuric  acid  remained  intact 
in  the  form  of  a  cellulose  sulphate.  This  behaviour  was  explained  by  the 
fact  that  the  sulphuric  acid  residue  in  these  esters  exists  in  the  form  of  —  S04H, 
which  is  readily  hydrolysed  by  the  action  of  water  or  acids,  but  becomes 
—  S04M  in  the  presence  of  alkalis,  towards  which  it  is  remarkably  stable.2  It 
has  been  possible  to  study  the  aceto-sulphates  more  thoroughly  than  the 
nitro-sulphates  because  a  larger  proportion  of  sulphuric  acid  can  be  made 
to  combine  in  the  former  case. 

It  was  shown  by  Robertson 3  that  the  sulphuric  esters  are  eliminated 
more  rapidly  from  the  gun-cotton  if  the  first  boilings  are  long,  that  is  not 
less  than  twelve  hours  each,  than  if  they  are  short.  The  reason  is  that  under 
these  conditions  the  material  is  in  contact  with  hot  dilute  acid  for  a  considerable 
time,  whereas  if  the  water  be  renewed  constantly,  the  alkalinity  is  restored 
each  time,  and  this  impedes  the  saponification  of  the  sulphuric  esters. 

Although  the  sulphuric  esters  are  hydrolysed  so  much  more  rapidly  by  Velocity  of 
acid  than  alkali  the  reverse  is  the  case  with  the  nitric  esters.     The  velocity  nftro^ellu-0 
with  which  a  nitro-cellulose  containing  12-84  per  cent.  N  is  hydrolysed  by  lose, 
solutions  of  barium  hydrate  at  a  temperature  of  39°  was  measured  by  Silberrad 
and  Farmer.4     They  found   that    the    velocity    is    given    by  the  equation  : 
q  (s  —  v)  =  lev,  in  which  q  is  the  quantity  of  nitro-cellulose  in  grammes  per 
400  c.c.  of  the  solution,  v  is  the  observed  velocity  with  which  the  alkalinity 
of   the   solution   diminishes   measured  in  gramme-equivalents   per  litre  per 
hour,  s  is  the  limiting  velocity  for  a  solution  saturated  with  nitro-cellulose, 
and  £  is  a  constant.     Further,  as  the  velocity  is  proportional  to  the  concentra- 
tion of  the  baryta,  the  equation  may  be  written  : 

CO. 3 

v  = 


k+q' 

c    being   the   concentration   of  the    baryta   in   gramme-equivalents   per  litre  ; 
s  =  0-168  and  k  =  26-5. 

For  hydrolysis  by  means  of  nitric  acid  the  values  found  for  these  constants 
were  s  =  0-000347  and  k  =  3-21.  Hence  when  the  proportion  of  nitro-cellu- 
lose to  liquid  is  high,  as  it  is  in  the  boiling  vats,  hydrolysis  is  about  480  times 

1  Ber.,  1905,  pp.  38  and   1859.  -  Briggs,  ./.  Soc.  Chem.   Ind.,   1906,  j>.  626. 

3  J.  Soc.  Chew.  />/</.,    mini.   p.   624.  *  Trans.  Chem,  Soc.,    1906,  p.   1759. 


190  EXPLOSIVES 

apid  in  an  alkaline  solution  as  in  an  acid  solution  of  equal  strength.  For 
this  reason  it  i-  unadvisable  to  use  strong  alkalis  for  the  stabilization  ;  caustic 
alkali-  should  be  avoided  and  sodium  carbonate  should  only  be  used  when 

water   otherwise    contains    no   alkali.     Hard    water   p< 

alkali  in  the  form  of  calcium  bicarbonate  without  any  addition,  and  this  is 
-•    suitable  for  stabilizing  nitro-celluloee.     V.  treatment  with 

og  alkali  i-  liable  to  convert  the  nitro-celluloee  into  unstable  decomposition 
product-. 

The  two  methods  <>f  stabilization  are  often  combined,  that  is  after 

the  nitro-cotton  has  been  boiled  and  pulped  it  is  again  boiled.     The  instruc- 
tions <»f  the  U.S.  Army  <  Ordnance  Department  as  revised  up  to  April  18,  1908, 
are.  f<>r  instant 
rs  Ordnance  .V'     '     ;      Ceflulosi    of  standard  quality  shall  be  dried  at  a  temperature 

not  exceeding  110°.  When  cold  this  cotton  shall  be  nitrated  in  mixed  nitric 
and  sulphuric  acids.  After  nitrating,  the  nitro-celluloee  shall  be  washed  in 
water  before  boiling. 

' '  /'  /. — The  nitro-celluloee  shall  be  boiled  at  least  forty 

hours,  and  with  not  less  than  four  changes  of  water,  in  tubs  so  constructed 
that  the  nitro-ceUulose  shall  not  come  in  contact  with  the  steam  at  a  tempera- 
ture greater  than  100°.  There  shall  be  complete  ebullition  or  boiling  over 
the  entire  surface  of  the  tubs.  Xo  alkali  shall  be  used  in  thi-  preliminary 
purification. 

"  Pulping. — The  nitro-cellulose  shall  then  be  pulped  in  fresh  water,  to 
which  shall  be  added  just  enough  sodium  carbonate  to  pn  -likdit  alkaline 

reaction   to   phenol-phthalein   solution;    the  pn        -     a   continued  until  the 
material  is  thoroughly  and  evenly  pulped  to  a  satisfactory  degree  of  fine]      - 
-   and  -how-  a  clean  break  when  a  handful  i-  squeezed  and  broken  into  parts. 
During  thi<  process  the  water  shall  be  changi  'ich  an  extent  as  may  be 

necessary  to  remove  the  impuriti-  - 

■  /'  -After  pulping,  the  nitro-cellulose  pulp  shall  be  run  to  the 

poachers,  settled,  and    the    water   decanted.     The    nitro-cellulose  shall  then 
be  boiled  six  hours  in  fresh  water,  and  during  thi>  time  not  more  than  1<> 
irbonate  of  soda  solution  for  each  2"»n>  lb.  dry  nitro-cellulose  may 
be  addt-.l  at   intervals.     T        -  -hall  contain  1  lb.  carbonate  of  - 

per  gallon.  During  t liis  and  all  other  boiling  in  the  poacher-  the  pulp  shall 
be  thoroughly  agitated  by  mechanical  stirrers.  After  boiling  the  nitro-cellu- 
lose -hall  be  allowed  to  settle,  and  the  clear  water  decanted  as  completely 
as  possible.     The  tube  -hall  then  be  tilled  with  fresh  water,  boiled  two  h< 

inted  and  refilled  with  fresh  water.     The  boiling  shall  then  be 
continued  for  one  hour,  and  this  pn ited  three  ti' 

This  make-  a  total  of  twelve  hours'  boiling  with  live  chang«-  <.f  water. 
viz.  »'.  2.  1.  1.  1.  1.     With  only  the  first  of  th<  addition  of  soda  allowed. 


THE   STABILIZATION   OF  NITROCELLULOSE  191 

"  After  boiling  the  nitro-cellulose  shall  have  ten  cold  water  washes,  each 
washing  to  consist  of  agitation  by  mechanical  means  for  half  an  hour  in  a 
sufficient  amount  of  fresh  water,  thorough  settling  and  decanting  the  clear 
water  ;  at  least  40  per  cent,  of  the  total  contents  of  the  poacher  shall  be  drawn 
off.  A  sample  shall  then  be  taken  for  subjection  to  the  various  tests  prescribed 
for  nitro-cellulose.  Should  the  nitro-cellulose  fail  to  meet  the  required  heat 
test,  it  must  be  boiled  again  with  two  changes  of  water,  the  time  of  actual 
boiling  being  five  hours  without  the  use  of  alkali,  and  then  it  must  be  given 
ten  cold  water  washes  in  the  manner  prescribed  for  the  regular  treatment." 

One  of  the  disadvantages  of  boiling  the  pulp  in  iron  hollanders  is  that  it 
may  be  necessary  to  add  alkali  to  neutralize  the  acid  formed.  It  is  better 
to  add  it  in  the  form  of  finely  divided  calcium  carbonate  (whitening)  than 
sodium  carbonate.  Another  disadvantage  is  that  the  water  cannot  be  removed 
nearly  as  completely  as  when  the  unpulped  nitro-cotton  is  boiled  in  wooden 
vats,  from  which  the  water  can  be  allowed  to  drain  very  thoroughly.  If  the 
pulp  be  allowed  to  settle  in  the  hollander  too  long,  it  forms  a  dense  mass  at 
the  bottom,  which  prevents  the  rotation  of  the  stirring  arms,  and  it  may  be 
necessary  to  dig  it  out. 

Another  class  of  unstable  products  that  may  be  present  in  nitro-cellulose  Cellulose 
is  that  of  the  nitrous  esters.     These  are  apparently  formed  in  the  hydrolysis  mtrites- 
of  nitro-cellulose  ;   on  treatment  with  dilute  alkali  or  acid  the  cellulose  residue 
becomes  oxidized  whilst  the  acid  residue  is  reduced.     The  nitrites  of  cellulose 
are  so  unstable,  however,  that  they  are  never  present  in  a  normal  product 
to  any  considerable  extent.     Nicolardot  and  Chertier  x  succeeded  in  preparing 
them  by  the  action  of  nitrous  acid  on  viscose  cellulose  suspended  in  dilute 
nitric  acid.     A  certain  amount  of  nitrate  is  formed  at  the  same  time,  but  this 
can  be  separated  from  the  nitrite  by  dissolving  it  in  acetone.     It  can  also 
be  made  by  passing  nitrous  gases  through  a  mixture  of  acetic  acid  and  acetic 
anhydride  in  which  viscose  cellulose  or  ramie  fibre  is  suspended.     The  products 
thus  prepared  are  of  a  grey  colour,  gelatinous  when  moist,  brittle  when  dry, 
insoluble   in   water,   alcohol,   ether,   acetone,    chloroform   and   ethyl-acetate. 
The  percentage  of  nitrogen,  as  determined  by  Schloesing's  method,  could  not 
be  obtained  higher  than  2-5  per  cent,,  that  is  to  say,  the  higher  nitrites  decom- 
posed before  they  could  be  analysed.     In  the  Lunge  nitrometer  they  gave 
no  evolution.     Even  those  with  2-5  per  cent,  gradually  evolve  nitrous  fumes 
at  the  ordinary  temperature,  and  water  and  strong  acids  split  the  nitrous 
acid  off  rapidly,  but  acetic  acid  has  little  effect .     It  is  possibly  the  presence 
of  these  nitrites  which  causes   unstabilized    gun-cotton  to  give  low  results 
when  tested  in  the  nitrometer.     It  is  found  that  on  boiling,  the  nitrogen  as 
determined   by  the  nitrometer  goes  up,  whilst  that  as  determined  by  the 
Schloesing    (Schultze-Tientann)    method    goes    down.     Although    nitrites    of 
1  Compt.  Rend.,  1910,   151,  p.   719. 


192  EXPLOSIVES 

cellulose  are  probably  formed  to  some  extent  in  the  nitration  process,  their 
presence  i-  to  be  ascribed  more  to  the  decomposition  of  the  nitric  esters. 
Their  presence  must  be  a  cause  of  instability. 

The  intermediate  products  formed  in  the  decomposition  of  nitrocellulose 
have  engaged  the  attention  of  various  investigators,  who  have  hoped  to  obtain 
evidence  as  to  the  constitution  of  the  cellulose  molecule.  Thus  Kerkhoff  J 
detected  tartaric  ami  citric  acids  among  the  products  of  saponification,  and 
Eladow  2  found  oxalic  acid  and  ammonia  and  an  acid  similar  to  saccharic. 
Divers*  found  in  the  decomposition  products  acids  which  from  their  reactions 
he  identified  as  pectic,  and  para-  and  meta-pectic  acids.  Abel4  continued 
the  presence  of  these  in  gun-cottons  that  were  badly  decomposed;  he  also 
found  formic  and  oxalic  acid-  and  cyanogen,  and  when  the  material  was 
heated  with  potash,  ammonia  was  given  off.  Fermentable  carbohydrates 
were  only  formed  in  a  few  instances.  Silberrad  and  Farmer5  extracted  with 
water  LOO  kg.  of  gelatinized  nitro-cellulose  powder,  which  had  been  heated 
for  twenty-three  weeks  at  .">4-4  .  In  the  extract  they  detected  ethyl  nitrite, 
ethyl  nitrate,  ethyl-alcohol  (these  evidently  derived  from  the  alcohol  used 
for  the  gelatinization),  nitric  and  nitrous  acids,  ammonia,  formic,  acetic, 
butyric,  dihydroxy-butyric,  oxalic,  tartaric,  isosaccharic  and  hydroxy-pyruvic 
acid-.  Carbohydrates  were  found  to  be  present  by  the  fermentation  tot. 
and  some  other  compounds  were  obtained,  but  could  not  be  identified  by 
ica -on  of  the  complexity  of  the  mixture  and  their  minute  quantity.  Hydroxy- 
pyruvic  acid.  c.;H4()4.  has  also  been  found  by  Will6  and  Vignon  7  among  the 
products  of  the  alkaline  saponification  of  nitro-cellulose  and  mtro-oxy-ceUuLose 
respectively.  Berl  and  Smith  8  obtained  it  (called  by  them  oxy-pyruvic  acid) 
by  the  alkaline  hydrolysis  not  only  of  nitro-cellulose  but  also  of  the  nit: 
of  glucose  and  Levulose,  showing  the  intimate  relationship  of  cellulose  with 
these  other  carbohydrates.  From  starch  nitrate  a  similar  but  not  identical 
acid  was  obtained.  They  also  found  that  hydroxy-pyruvic  acid  i>  very 
Busceptible  to  oxidation  and  fermentation,  and  consequently  may  be  the 
substance  which  others  have  described  as  ''fermentable  carbohydrates." 
Berl  and  Fodor  9  found  that  the  relative  proportions  of  the  different  acids 
formed  vary  according  to  the  concentration  of  the  alkali  used,  a  dilute  solution 
yielding  compounds  containing  4  to  5  carbon  atoms,  whilst  with  concentrated 
alkali  acids  with  1  to  3  carbon  atoms  predominated.  In  addition  to  hydroxy- 
pyruvic  acid  they  detected  malic,  trihydroxy-glutaric.  malonic.  tartronie. 
oxalic,  glycollic  and   dihydroxy-butyric  acid-. 

1  J.   i.  prakt.  ('..   1*47.  p.  284.  2  J.  Chem.  Soc,   1854.  p.  201. 

3  J.  Chi        -         1863,  ]».  91.  *  Phil.   Trans.,   1*«>7.  p.   181. 

'■  •/.  Chem,  Soc.,   1906,  p.    1182.  6  Ber.,    1891,  pp.  400,  ."831. 

'"/-/.  /,'./,'/..   L907,  p.   B72.  s  •/.  Soc.  Chem.   Ind.,   1908,  p.  534. 

v.   1910,  pp.  296,  313. 


THE    STABILIZATION   OF    NITRO-CELLULOSE  193 

Berl  and  Fodor  1  have  also  examined  the  nitrogenous  residues  left  on 
treatment  with  alkali.  A  solution  of  collodion  cotton  was  shaken  for  several 
weeks  with  a  dilute  solution  of  sodium  carbonate.  At  the  surface  between 
the  two  liquids  a  flocculent  substance  separated  out,  which  was  found  to 
contain  8-4  per  cent,  nitrate  nitrogen  as  determined  by  the  nitrometer,  and 
90  per  cent,  total  N  by  the  Dumas  method.  The  same  substance  was 
separated  from  the  ether-alcohol  solution  after  the  unchanged  nitro-cellulose 
had  been  removed  by  precipitation  with  water.  When  the  aqueous  liquid 
thus  obtained  was  acidified  a  precipitate  was  obtained  (also  a  slight  smell  of 
prussic  acid),  and  this  was  purified  by  dissolving  in  96  per  cent,  alcohol  and 
reprecipitating  with  water.  The  action  of  caustic  potash  on  collodion  cotton 
in  solution  also  yielded  the  same  substance.  It  was  soluble  in  alcohol  but 
insoluble  in  ether  ;  on  analysis  it  gave  results  agreeing  with  the  formula 
C24H3  3021(N02)5,  and  may  therefore  be  considered  as  a  penta-nitro-oxy- 
cellulose.  It  differed  from  normal  penta-nitro-cellulose  in  having  two  hydro- 
gen atoms  replaced  by  one  oxygen.  Its  solutions  showed  little  viscosity, 
and  molecular  weight  determinations  gave  results  agreeing  fairly  well  with 
the  formula.  The  authors  gave  the  substance  the  name  "  cellonic  acid  nitrate." 
Besides  this  another  substance  was  obtained,  which  was  soluble  in  ether. 
This  was  considered  to  be  cellonic  acid  nitrite.  The  cellonic  acid  nitrate 
was  not  very  stable  ;    it  exploded  at   163°. 

Will  and  Lenze  2  considered  that  the  instability  of  some  samples  of  nitro- 
cellulose may  be  due  to  the  formation  of  sugars  from  the  cellulose,  and  the 
conversion  of  these  into  nitrates.  They  accordingly  prepared  and  examined 
various  nitrates  of  the  carbohydrates  (see  next  chapter),  which  they  found  to 
be  all  more  or  less  unstable.  Sugar  nitrate  cannot  be  formed  in  the  nitration 
of  cellulose,  however,  unless  the  sugar  be  present  beforehand,  as  the  nitration 
is  a  much  more  rapid  reaction  than  the  formation  of  sugar  from  cellulose,  and 
although  sugars  are  apparently  formed  sometimes  in  the  decomposition  of 
nitro-cellulose,  they  are  among  the  products  of  the  ultimate  breaking  down 
of  the  material,  and  they  are  no  longer  nitrated.  The  presence  of  these  foreign 
carbo-hydrates  should  be  excluded  from  the  cellulose  used  for  nitration  ; 
starch  is  the  one  that  is  most  likely  to  occur. 

Collodion  cotton  for  the  manufacture  of  blasting  gelatine  is  not  boiled,  Washing 
because  the  power  of  forming  a  stiff  colloid  would  thereby  be  much  reduced.  cotton. 
It  is  washed  repeatedly  with  hot  water  slightly  below  the  boiling-point. 

1  S.S.,  1910,  pp.  254,  269.  2  Ber.,  1898,  p.  (58. 


vol.  i.  13 


CHAPTER   XIV 

NITRIC  ESTERS   OF  OTHER   CARBOHYDRATES 

Nitro-starch  :    Nit: 

Nitro-starch.  Nitro-starch  has  been  known  even  longer  than  nit  ro-  cot  ton,  for  it  was  first 
prepared  by  Braconnot  in  1833  *  by  dissolving  starch  in  strong  nitric  acid 
and  pouring  the  viscous  translucent  liquid  into  water.  The  resulting  cheesy 
white  substance  was  called  by  him  '*  xyloidine,"  a  name  which  is  now  applied 
generally  to  any  product  that  is  made  by  dissolving  a  carbo-hydrate  in  nitric 
acid  and  pouring  into  water  or  sulphuric  acid,  or  by  dissolving  in  sulphuric 
acid  and  pouring  into  nitric.  Nitro-starch  was  afterwards  investigated  by 
Pelouse.2  Liebig.  Buijs-Ballot.  Gerhard.  Bechamp.3  and  Reichardt.  In  spite 
of  the  cheapness  of  the  raw  material,  starch,  it  lias  never  been  able  to  displace 
nitro-cotton  ;  this  is  partly  due  to  the  instability  of  nitro-starch.  and  partly 
to  the  mechanical  difficulties  in  nitrating  and  purifying  it.  If  the  starch  be 
introduced  into  the  mixed  acids  in  the  same  way  that  cotton  is.  it  forms  clots, 
which  are  not  thoroughly  acted  upon,  and  are  difficult  to  purify  subsequently. 
Hence  in  all  the  early  attempts  to  manufacture  the  substance  the  starch  was 
.  dissolved  in  nitric  acid  and  poured  into  sulphuric  acid.  Such,  for  instance, 
was  the  method  of  tin-  Austrian  engineer  officer  Uchatius.4  The  process 
the  Viennese  Nobel  Company s  consisted  in  dissolving  ground  starch  in  intric 
acid  (specific  gravity  1-501).  and  then  injecting  it  as  a  spray  into  the  waste 
acids  from  nitro-glycerine  [HNO,  10  per  cent..  H..S04  To  per  cent..  H  ,<  I  20 
per  cent.),  the  temperature  being  kept  down  to  20°  to  26°.  The  nitro-starch 
was  then  filtered  off  on  a  filter  of  gun-cotton,  washed  with  water  and  treated 
for  twenty-four  hours  with  5  per  cent.  soda.  It  was  then  ground  to  a  paste 
and  washed  in  a  centrifugal  or  filter-press  and  impregnated  with  aniline  with 
the  object  of  making  it  stable.  Until  it  was  required  for  further  use  it  was 
kept  wet.  containing  about  33  per  cent,  water  and  1  per  cent,  aniline. 

1  Ann.  rhini.  }>htjs..  58,  p.  290. 

2  Aim.  pkarm.,  1830.  (20),  p.  38;    CompL  Bend.,  83,  p.   - 

3  Ann.  chim.  phys..    1862.  p.   311. 

4  Dingkr's  Poly.  Joum.,    1861,   p.    146.  5   Genu.   l'at.   57.711. 

194 


NITRIC   ESTERS   OF   OTHER   CARBOHYDRATES 


195 


Hough's  process  x  differs  from  previous  ones  in  that  he  injects  powdered 
starch  by  means  of  a  jet  of  air  into  mixed  acid  containing  an  excess  of  sulphuric 
anhydride,  which  excess  is  maintained  during  nitration  by  the  addition  of 
more  oleum.  The  nitrated  product  is  filtered  off  and  treated  with  hot 
ammonia.  He  claimed  thus  to  obtain  a  stable  product  containing  about 
16-5  per  cent.  N.  These  claims  have  been  investigated  by  Berl  and  Butler,2 
only  they  did  not  treat  the  product  with  alkali,  as  this  could  only  have  an 
injurious  effect  on  the  stability  :  they  treated  it  with  water  only.  They 
found  that  the  products  were  very  unstable,  the  heat  tests  low,  as  also  the 
ignition  points,  and  they  contained  0-50  per  cent,  combined  sulphuric  acid. 
The  percentage  of  nitrogen  also  was  very  much  lower  than  as  stated  by  Hough  ; 
in  no  case  was  it  more  than  about  13-4  per  cent.,  which  was  the  same  as  nitro- 
cotton  contained  when  it  was  nitrated  in  the  same  manner. 

The  Nobel  and  other  methods  Mere  similarly  investigated  by  Miihlhauser.3 
The  principal  results  are  collected  together  in  the  following  Table  : 


Per  cent. 
N. 

Solubility  in 

Ignition 
Point 

Remarks 

Method  of  Preparation 

a  i     ii       Ether- 
Alcohol       . ,     ,     , 
1  Alcohol 

Pptd.  with  N/G  waste  acic 
„     water 

„     3-5  pts.  H2S04 
„     3 
„      3 
Injection.     Wheat  starch 
Potato       .. 
,,              Rice          ,, 
.,              Soluble      „ 

11  02 
10-54 
12-50 
12-87 
13-32 
13-23 
13-44 
12-86 
13-35 

sol. 
insol. 

sol.            175° 
170° 
121° 
152° 
155° 
dif.  sol.        121° 
120° 

sol.            135° 
120° 

M,  Nobel  process 

M 

M 

M 

M 

B,  Hough  process 

B,       „ 

B,       „ 

B,       „ 

M  means  investigated  by  Muhlhausen  ;    B  by  Berl  and  Butler. 

None  of  these  were  stable  except  the  first  two,  which  contained  only  11 
and  10-5  per  cent.  N  respectively,  but,  on  the  other  hand,  Will  and  Lenze,4 
by  treatment  with  solvents,  obtained  a  stable  product  with  1404  per  cent. 
N.  To  prepare  this  they  dissolved  the  dried  starch  in  concentrated  nitric 
acid  (specific  gravity  1-52),  which  was  kept  cool,  and  after  twenty-four  hours 
sulphuric  acid  was  gradually  added.  The  product  was  washed  with  water, 
then  extracted  first  with   cold  alcohol  and  afterwards  twice  with  hot  alcohol. 

1  U.S.  Pats.   751,076  of  February  2,   1904,  and  790,840  of  May  23,   1905. 

2  S.S.,   1910,  p.  82.      3  Dingier' a  Polyt.  Jour.,   1892  (284),  p.  37.      *  Ber.,  1898,  p.  68. 


196  EXPLOSIVES 

It  was  dissolved  in  a  mixture  of  acetone  and  alcohol  and  the  acetone  evaporated 
off,  thereby  precipitating  the  nitrate  as  a  white  powder.  This  was  then 
boiled  with  alcohol,  washed  with  water  and  dried.  The  product  purified  in 
this  way  ignited  only  at  li>4°,  and  after  keeping  at  50°  for  six  months  was 
still  quite  stable.  Such  a  process  is,  of  course,  quite  unsuitable  for  use  on 
a  commercial  scale,  but  it  Beems  to  indicate  that  nitro-starch  itself  is  fairly 
stable  if  it  can   be  separated  from  impurities. 

Nitro-starch  dissolves  readily  in  acetone  and  ethyl-acetate.  The  solu- 
bilities in  alcohol  and  ether-alcohol  are  given  in  the  above  'Fable.  That  made 
by  the  Nobel  process  dissolves  very  readily  in  nitro-glycerine,  but  docs  not 
gelatinize  it  as  collodion  cotton  doc-.  This  is  in  accordance  with  the  low 
viscosity  of  the  solutions  in  acetone.  Berl  and  Butler  obtained  the  following 
viscosities  for  solutions  of  potato  starch  nitrated  by  Hough's  method  and 
for  nitro-collulose  nitrated  in  the  same  way.  both  containing  13-4  per  cent.  N. 

1  per  cent.  2  per  cent.  5  per  cent, 

solution  solution  solution 

Potato  starch  nitrate  .  .        1-74  ..  2-66  ..  0-47 

Cellulose  nitrate         .  .  .     95-1  ..  1,005  ..         85,640 

Acetone  =  1 

Other  varieties  of  starch  gave  even  lower  viscosities.  The  molecular  com- 
plexity is  in  fact  small:  Saposhnikoff a  determined  the  molecular  weight  in 
a  Beckmann  apparatus  with  boiling  acetone  for  two  different  product-  each 
containing  13-4  per  cent.  X.  and  obtained  results  agreeing  with  a  C:.,;  formula. 
One  of  the  disadvantages  of  nitro-starch  as  compared  with  nitro-cotton 
lies  in  the  fact  that  it  absorbs  a  much  larger  amount  of  moisture  from  the 
air,  just  as  starch  is  more  hygroscopic  than  its  homologue,  cellulose.  Thus 
Will2  found  that  the  materials  after  being  dried  in  an  oven  at  40°  took  up 
the  following  amounts  in  an  atmosphere  nearly  saturated  with  moisture  at 
25°: 


Cotton      ..... 
Wheal   starch    .... 

Maize  ,,.... 

Potato 

Rice         ,,.... 

Soluble     ,,.... 

and  the  corresponding  figures  for  the  nitrated  products  were  found  by  Will 
and  Berl  and  Butler  to  be  . 

1  ./.  Ruaa.  Phya.  Chetn.  Soc,   1903,  p.   12G  ;    J.  Chcm.  Soc.  Abs.,   1903,  p.  402. 

2  Mitt,  ".  'I.  CentralateUe,  X".  4. 


Hygroscopic! 
(per  cent) 

ty 

.    7  to  8 

11-4 

10-6 

141 

11-4 

11-3 

NITRIC  ESTERS   OF   OTHER  CARBOHYDRATES 


197 


Rice  starch  nitrate  (\Y) 
Soluble  „  „        (W) 

Potato    „  „        (B) 


Per  cent.  N 


8-51 
12-95 
13-44 


Hygroaeopicity 


7-37 
8-40 
6-57 


Hygroscopicity 
of  nitro-cotton 
with  same  per- 
centage N° 


6-1 
1-6 
1-2 


Nitro-starch  has  never  come  into  general  use  in  Europe,  principally  because 
of  its  unsatisfactory  stability,  in  spite  of  the  efforts  of  Uchatius  and  the  Austrian 
Nobel  Company  to  make  smokeless  powders  .with  it.  It  is  not  authorized 
for  manufacture  or  importation  into  England.  In  America,  however,  it  is 
used  as  a  component  of  high  explosives. 

By  the  action  of  nitric  acid  on  various  sugars  products  can  be  obtained  Nitro-suga 
containing  16  to  17  per  cent.  N.  They  can  be  exploded  by  friction  and  go 
off  with  great  violence.  Attempts  have  therefore  been  made  to  use  them 
for  percussion-caps,  but  they  have  hitherto  proved  too  sensitive,  too  hygro- 
scopic, and  too  liable  to  spontaneous  decomposition.  A  number  of  these 
substances  were  prepared  and  examined  by  Will  and  Lenze.1  The  general 
method  of  preparation  was  to  dissolve  the  sugar  in  nitric  acid,  add  sulphuric 
acid,  separate,  wash  with  ice  water,  and  purify  by  recrystallization  from 
alcohol.     The  following  Table  gives  the  principal  results  : 


Melting- 

point 

Monosaccharides — 

Pentoses,  C5H10O6  : 

Rhamoose  tetranitrate 

135° 

Arabinose            ,, 

85° 

Xylose                 ,, 

141° 

Per  cent. 

N 


Hexoses,  C6H1206  Aldoses  : 
Glucose  pentanitrate 

Galactose         ,, 

Mannose  ,, 

Ketosea  : 

Levulose  trinitrate 

Sorbinose        ,, 


ft 


10° 

115°-116° 

72°-73° 

81°-82° 

137°-139c 

48°-52° 
40°-45° 


1608 
16-75 

14-57 

16-96 
1718 
17-08 
17 

14-12 
13-83 

14-04 


Loss  at  50° 


Decom- 
poses at 


1-2%  in  30  days 
1-5%  in  1  day 
40%  in  40  days 


38%  in  1  day 
42%  in  10  days 
42%  in  1  day 
46%  in   1  day 

0  in   180  days 
1-3%  in  8  days 


120c 


135° 
126° 
125° 
124° 

145° 
135° 


1  Ber.,   1898,  pp.  68-90. 


L98 


EXPLOSIVES 


Mi-li     _ 

1-  -  • 

point 

N 

poses  at 

Monosaccharides — (< 

II.                   -H1407  : 

Ghiooheptoee  hexaniti 

100* 

17-39 

— 

— 

Oli. 

a-Methylglucoskle 

nitrate. 

■    14 

3 

l:;.v 

(i-Mfthyl-il-iiKiiiii 

nitrate. 

15 

— 

— 

Dtsaccharides.   C 12H ::On  : 

1                 _            '    nitrate 

28     - 

" 

11%  in  3  d 

■ 

.. 

14.-.     14 
163     164    ' 

15-48 

I 

" 

16-40 

in  4<>  d 

Ma.' 

- 

in  11  d 

■4' 

in   43  d 

Treli 

llM 

16-11 

— 

TRISACCHAR] :      -             :  :  ,  _«  >  u  : 

Raffinoee  endekaniti 

55 

15 

136* 

The  product  from  levulose  appear.-  to  be  the  most  stable  ;   those  from  maJ 
and  lactose  also  did  not  decompose  very  readily. 


PART  V 

NITRIC  ESTERS  OF  GLYCERINE 


CHAPTER    XV 
GLYCERINE 

Source  of  glycerine  :    Soap  boiling  :    Purification  of  spent  lye  :    Concentration  : 
Autoclave  process  :    Combined  process  :    Twitchell  process  :    Ferment  process  : 

Distillation 

Glycerine,  C3H803,  is  a  by-product  in  the  manufacture  of  soap  and  stearme  Source  oi 
candles  from  oils  and  fats,  which  consist  almost  entirely  of  the  glycerides  of  G1ycenne- 
the  fatty  acids,  compounds  formed  by  combining  three  molecules  of  a  fatty 
acid,  stearic  acid  for  instance,  C17H35C02H,  with  one  of  glycerine  and  eliminat- 
ing three  molecules  of  water.     When  the  oils  or  fats  are  heated  with  solutions 
of  caustic  alkalis  or  acids,  or  even  with  water  alone  the  glyceride  is  split  up  : 

3H20      +     C3H5(C17H35CO,)3     =     C3H5(OH)3     +      3C17H35C02H 

Water  Tri?tearine  Glycerine  Stearic  acid 

If  caustic  soda  has  been  used,  it  combines  with  the  acid  to  form  a  soap  such 
as  sodium  stearatc,  C17H35C02Na.  Stearine  candles,  on  the  other  hand,  are 
made  from  the  free  fatty  acid  and  principally  from  stearic  and  palmitic  acids. 

The  soap  industry  is,  of  course,  a  very  old  one,  but  it  is  only  in  modern 
times  that  the  recognition  of  the  advantages  of  cleanliness  has  caused  it  to 
assume  really  large  dimensions.  Formerly  the  glycerine  was  either  left  in 
the  finished  soap,  or  was  allowed  to  run  to  waste.  It  is  only  since  the  develop- 
ment of  the  industry  of  nit ro -glycerine  explosives  that  there  has  been  a  large 
demand  for  the  product.  The  demand  for  glycerine  for  the  manufacture  of 
explosives  is  now  so  great  that  it  often  absorbs  all  the  available  supplies. 
The  European  production  is  estimated  at  80,000  or  90,000  tons  per  annum. 
It  now  pays  the  soap-maker  to  recover  a  much  larger  proportion  of  the  glycerine 
than  formerly. 

The  simplest  method  of  making  soap  is  to  boil  the  oil  with  caustic  soda  soap-boili 
solution  in  open  tanks  ("  kettles  "),  which  usually  hold  40  to  50  tons.  The 
saponification  is  started  with  a  weak  lye  of  specific  gravity  105  (40  per  cent. 
XaOH),  and  when  the  action  is  well  started  stronger  lyes  are  added.  When 
the  action  is  almost  complete,  salt  is  added  to  render  the  soap  insoluble  in 
the  water.  Two  layers  are  thus  obtained  :  an  upper  one  of  soap,  and  a  lower 
one  of  brine  containing  the  glycerine  dissolved  in  it.     The  soap  is  separated, 

201 


_  .  EXPLOSIVES 

the  saponification  is  completed  by  the  addition  of  a  little  more  soda,  and  it 
ibmitted  to  such  further  pi  ssary  to  produce  the  class 

of  soap  requii- 

There  are  a  number  of  other  pr<  splitting  up  the  fats  with  separa- 

tion of  the  fatty  aci  -  .  h,  and  these  acid-  can  subsequently  be  combined 
with  soda  to  form  soaps.  These  methods  have  been  used  largely  in  Germany 
for  soap-making,  but  the  manufacture  of  soap  is  thus  rendered  much  more 
difficult  ;  the  soap  is  often  dark  in  colour,  and  is  apt  to  "  grain  "  on  keeping, 
and  in  man j  rancid.     These  disadvantages  more  than  compen- 

for  the  fact  that  the  recovery  of  the  glycerii  er.     In  England 

nification  with  soda  is  practically  universal,  and  it  is  the  process  most 
I  in  America.     The  tendency  in  Germany  is  also  to  return  to  tins  method 
for  the  manufacture  of  soap, 
onfication of         The  spent  lye  conta:  Les  glycerine  and  much  water,  a  large  amount 

sodium   chloride,  and  various  impurities,   organic  and  inorganic.     It   is 
first  necessary  to  remove  Home  of  the  impurities.     The  tree  alkali  is  first 
neutralized  with  sulphuric  or  hydrochloric  acid,  and  if  impure  soda  has  been 
;.  ferric  or  aluminium  chloride  is  added  as  long  a>  a  precipitate  is  formed 
free  the  liquid  from  hypo-sulphites,   sulphides,   cyanides,   sulpho-cyanides, 
etc.     The  precipitate,  which  is  allowed  to  settle,  contains  Prussian  blue  and 
fatty  matters,  which  are  recovered.     Other  methods  of  purification  are  also 
'pted  according  to  the  composition  of  the  lye. 
oucentraticn.        The  next  to  concentrate  the  lye.     During  this  operation  considerable 

quantiti-  -     E  salt  separate  and  cause  trouble  by  coating  the  solid  surfaces 
and  preventing  the  transmission  of  heat.     Various  types  of  plant  have  been 
devised  for  earning  out  this  operation,  Buch  as  that  of  L.  Droux,  of  Paris, 
consisting  of  a  steam-heated  drum  revolving  in  a  shallow  tank  rilled  with  the 
liquid  ;    the  removal  of  the  salt  is  easy  with  a  plant  of  this  kind.     At  the 
sent  time  the  concentration  is  usually  carried  out  in  single  or  multiple 
effect  vacuum  evaporators,  in  which  the  liquid  is  kept  circulating  rapidly, 
nat  solid  deposits  may  not  be  formed  on  the  heating  surfaces. 
If  the  fatty  acids  are  to  be  used  for  the  manufacture  of  candles,  other 
pro*  treating  the  oil  or  fat  can  he  used,  as  the  adds  have  to  be  distilled 

0  in  any  case,  in  order  to  remove  the  dark-coloured  impurities.     It 
is  ah  ive  from  them  oleic  acid,  which  has  a  melting-point  of 

only  14".  and  would  consequently  make  the  material  too  soft  ;  the  melting- 
pointe  :  stearic  and  palmitic  acids  arc  48*  and  62  respectively.  This  is 
effected  partly  by  filtration  and  partly  by  distillation. 

The  method  which  was  first  used  for  the  manufacture  of   Btearine  was  to 

nify  with  an  excess  of  milk  of  lime,  separate  the  glycerine  from  the  lime 

soap,  and  decompose  the  latter  with  sulphuric  acid.     The  consumption  of  lime 

and  sulphuric  acid  \  siderable,  however,  and  the  process  was  trouble- 


GLYCERINE  203 

some.  Then  it  was  found  that  a  much  smaller  proportion  of  lime  would  suffice, 
if  the  operation  were  carried  out  at  a  high  temperature  and  pressure.  The  . 
treatment  is  effected  at  a  pressure  of  about  120  lb.  per  square  inch  in  an  auto-  process*™ 
clave,  provided  with  a  mechanism  for  stirring.  A  little  zinc  oxide  is  also 
added  sometimes  to  hasten  the  reaction.  According  to  Lewkowitsch1  the 
yield  of  "saponification  crude  glycerine"  of  specific  gravity  1-240  by  this 
process  is  about  10  per  cent. 

It  is  possible  to  do  away  with  the  lime  entirely,  and  resolve  the  fat  into 
acids  and  glycerine  by  merely  heating  with  water  in  an  autoclave,  but  the 
temperature  required  is  high  and  the  time  long,  and  consequently  there  is 
much  decomposition,  with  the  result  that  the  yields  are  bad  and  the  products 
impure.  But  instead  of  alkaline  substances  such  as  caustic  soda  and  lime, 
many  other  materials  may  be  used  to  accelerate  the  saponification.  One  of 
these  is  sulphuric  acid,  which  is  much  used  for  the  production  of  candle  stearine. 
The  fat  is  heated  to  about  120°  and  mixed  intimately  with  4  to  6  per  cent, 
of  C.O.V.  The  yield  of  glycerine  by  this  process  is  only  8  or  9  per  cent.  ;  the 
acids  are  very  dark  in  colour,  but  a  large  yield  is  obtained  of  material  suitable 
for  candle  making,  61  to  63  per  cent,  as  against  45  to  47  per  cent,  by  the  auto- 
clave process.  This  is  due  to  the  action  of  the  sulphuric  acid  upon  the  oleic 
acid,  which  is  converted  into  iso-oleic  and  hydroxy-stearic  acids,  stearo-lactone 
and  other  bodies  having  comparatively  high  melting-points.  Unfortunately 
some  of  these  are  broken  down  again  in  the  subsequent  distillation. 

The  advantages  of  both  processes  can  be  combined  by  first  heating  in  an  Combined 
autoclave  with  a  small  proportion  of  lime,  and  subsequently  treating  the  fatty  process- 
acids   with    concentrated   sulphuric    acid.     According   to  Lewkowitsch 2   the 
yields  from  100  parts  tallow  are  then  : 

Candle  material      ......  61-63  parts 

Oleic  acid 30-32     „ 

Crude  glycerine  (s.g.   1-240)     .  .  .  .         10        , 

Pitch  and  loss         ....  2-3 

In  the  Twitchell  process 3  the  fat  is  treated  with  a  reagent  made  by  the  Twitcheii 
action  of  sulphuric  acid  on  oleic  acid  dissolved  in  an  aromatic  hydro-carbon,  "' 
such  as  naphthalene.  This  reagent  greatly  accelerates  the  hydrolysis  of  the 
fat,  but  it  is  not  known  how  it  acts.  The  fat  mixed  with  |  to  1  per  cent,  of 
the  reagent  and  some  water  is  boiled  for  twelve  to  twenty-four  hours  with 
live  steam  in  a  tank  closed  to  prevent  access  of  air,  which  would  make  the 
acids  dark.  The  fatty  layer  now  contains  85  to  90  per  cent,  of  free  fatty 
acids.  The  contents  of  the  tank  are  allowed  to  settle,  and  the  aqueous  layer 
containing  the  glycerine  is  drawn  off.     A  small  quantity  of  water  is  1  hen  added, 

1  Oils,  Fats  and   Waxes,  4th  ed.,  vol.  hi.,  p.    178.  2  Loc.  til.,  p.    188. 

3  Amer.  Pat.,  601,  603,  March  29,   1898. 


process. 


204 


EXPLOSIVES 


and  the  boilii  g  ia  continued  for  another  twelve  to  twenty-four  hours.     The 
conversion  ia  then  97  to  98  per  cent.     Barium  carbonate  is  then  added  until 
the  water  is  neutral  to  methyl  orange,  as  the  presence  of  strong  acidf 
tin-  materia]  to  discolour.     This  process  is  much  used  in  America  for  the 
manufacture  of  candle  material. 

Another  catalytic  agent  that  is  used  to  accelerate  the  saponification  of 
fats  is  the  enzyme  contained  in  castor-oil  seeds  I  gent  is  prepared 
by  decorticating  the  seeds,  grinding  them  up  with  water,  and  allowing  them 
to  ferment.  A  creamy  emulsion  rises  to  the  Burface  containing  some  4  per 
cent,  of  albumenoid  Bubstances,  which  constitute  the  active  agent.  The  oil 
to  be  Baponified  is  mixed  with  about  4n  per  cent,  of  water  and  stirred  to  an 
emulsion  by  mean-  of  air,  5  to  8  per  cent,  of  '*  ferment  '"  are  added,  and  n-2 
per  cent,  of  manganese  sulphate,  which  greatly  assists  the  action.  The  whole 
mass  is  kept  at  a  suitable  temperature,  which  should  not  be  ab<  ve  35  .  hut 
must,  of  course,  be  higher  than  the  melting-point  of  the  fat.  In  the  case  <>f 
fat  of  high  melting-point  it  is  necessary  to  mix  it  with  oil.  The  fermentation 
i-  allowed  to  proceed  for  one  or  two  days,  and  if  the  »  mulsion  -how-  -i;_rii-  of 
-et t ling  out.  it  i<  stirred  up  again  with  air.  It  i-  not  practicable  to  attain 
much  more  than  80  per  cent,  conversion  by  this  process.  When  it  i>  finished  a 
little  sulphuric  acid  is  added  to  cause  the  emulsion  to  separate,  and  the  tem- 
perature i>  raised  to  about  80  to  destroy  the  enzymes.  Some  difficulty  is 
caused  by  the  slowness  with  which  the  emulsion  separates  out  ;  the  incom- 
pleteness of  the  conversion  i-  also  an  objection.  The  advantages  of  this 
and  the  Twin-hell  process  are  that  the  plant  required  i>  very  simple  and  in- 
expensive, and  the  colour  of  the  acid-  i-  g I.     The  Losses  by  either  may 

1>«-  heavy,  however,  if  they  are  mishandled. 

Glycerine  that  i-  to  lie  used  for  the  manufacture  of  nitro-glycerine  ha-  to 
be  purified  by  distillation.  At  one  time  the  distillation  was  carried  ouf  at 
atmospheric  pressure  with  superheated  -team  in  a  -till  heated  by  a  tire.  Under 
these  conditions  much  of  the  glycerine  was  decomposed  and  polyglycerines 
were  formed.     Distillation  with  saturated  .-team  w  ;;<1  not  give  good 

results,  because  the  temperature  of  the  -team  was  reduced  too  much  by  the 
expansion.  The  distillation  i-  now  generally  carried  out  with  superheated 
-team  ii  vacuo.  There  i<  no  great  difficulty  in  separating  the  glycerine  from 
the  water  in  tin-  distillate,  a-  the  boiling-points  are  very  far  apart  (290  and 
ion  respectively  at  atmospheric  pressure),  hut  the  distillation  must  be  carried 
out  with  proper  'are  to  obtain  the  glycerine  in  a  satisfactory  state  of  purity. 
The  glycerine  is  generally  condensed  in  a  series  of  metal  pipes  cooled  by  ex- 
posure to  the  air.  In  the  first  tubes  practically  anhydrous  glycerine  con- 
denses :  in  the  later  one-  the  condensate  i-  somewhat  dilute.  The  former  only 
i-  n-eil  for  the  manufacture  of  nitro-glycerine.  the  latter  for  a  variety  of  pur- 
poses, such  a-  filling  gas-meters,  the  manufacture  <>\  ink  and  sizes  for  textile-. 


GLYCERINE 


205 


Fig.  38  shows  a  distillation  plant  of  the  type  made  by  George  Scott  and  Sons, 
London,  and  very  largely  used  in  England.  Over  the  vertical  still  shown  in 
the  background  is  a  catch-pot,  in  which  high  boiling  impurities,  such  as  poly- 
glycerines  are  condensed,  and  material  such  as  salt,  that  is  carried  along 


Fig.   38.     Distillation  Plant  for  Glycerine 


mechanically  by  the  vapours,  is  held  back.  After  passing  through  the  air- 
cooled  battery,  shown  in  the  foreground,  in  which  the  glycerine  is  condensed, 
the  vapour  passes  to  a  condenser  cooled  with  water,  where  the  water  is 
condensed,  and  then  to  a  vacuum  pump.  The  cost  of  distillation  is  stated  to 
be  about  £1  per  ton. 


CHAPTER   XVI 
MANUFACTURE   OF  NITRO-GLYCERINE 

Early  methods  :  Injector  :  Modern  plant  :  Nitrator  :  Separator  :  Pre -wash 
tank  .  Washing  :  Filtering  :  Wash-waters  :  After-separation  :  Recent  im- 
provexnentfi  :  Abolition  of  cocks  :  Funic  hoods  :  Plugs  for  air-holes  :  Soften- 
ing the  washing  waters  :  Washing  operations  :  Labyrinths  :  Xitrator-separa- 
tor  :  Cooling  coils  :  Prevention  of  after-separation  :  Drowning  arrangement  : 
Adds  and  yields  :  Time  of  separation  :  Conveyance  of  nit  ro -glycerine  :  Guttc : 
Location  of  factory:  Air-supply:  Limit  boards:  Thunder-storms:  General 
precautions  :    Sensitiveness. 

In  the  early  days  nitroglycerine  was  made  on  quite  a  small  scale  by  hand. 
The  mixed  acids  were  placed  in  a  pot  of  iron,  lead,  or  earthenware,  surrounded 
by  a  trough  containing  cold  water.  The  glycerine  was  then  poured  in  slowly 
while  the  liquid  was  stirred  by  means  of  a  rod  of  iron  or  glass.  The  yield 
obtained  was  sometimes  as  much  as  2  Lb.  of  nitro-glycerine  from  1  lb.  of 
glycerine,  but  was  frequently  considerably  less.  After  all  the  glycerine  had 
been  added,  the  stirring  Mas  continued  for  a  few  minutes  longer,  then  the  liquid 
was  allowed  to  stand  and  the  nitro-glycerine  was  skimmed  from  the  surface 
and  poured  into  water,  with  which  it  was  agitated.  Finally  it  was  separated 
from  the  water  by  means  of  a  separating  funnel.  With  the  development  of 
the  dynamite  industry  the  demand  for  nitro-glycerine  grew  enormou.-ly, 
and  mechanical  appliances  were  gradually  introduced  to  enable  larger  quantities 
to  be  dealt  with  at  a  time,  thus  saving  labour  and  improving  the  yield.  De- 
scriptdons  of  these  are  to  be  found  in  the  older  text-books,  such  as  those  of 
Guttmann  and  (  halon. 

A  few  years  after  the  discovery  of  dynamite  by  Xobel  in  1866  most  of  the 
essential  features  of  the  modem  plant  had  been  introduced.     The  nitrating 

•  1  was  a  large  cylindrical  leaden  tank  with  an  outer  wooden  casing,  form- 
ing a  jacket  through  which  cold  water  was  circulated.1  In  the  tank  there 
were  also  coils  through  which  cold  water  ran.  Agitation  was  effected  by 
means  of  compressed  air  led  in  through  lead  pipes,  and  in  the  earlier  plants 
mechanical  agitation  \\as  also  employed.  The  glycerine  Mas  run  in  from  a 
tank  placed  above  the  nitrator  through  a  cock  by  means  of  which  the  inflow 
1  8§e  Nathan  and  Rintoul,  J.  Soc.  Chem.  Ind.,   1908,  p.   194. 

206 


MANUFACTURE   OF  NITROGLYCERINE  207 

was  controlled.  The  fumes  passed  away  through  a  glass  pipe,  which  enabled 
the  man  in  charge  to  observe  their  colour.  He  also  watched  the  temperature 
by  means  of  a  long  thermometer,  the  scale  of  which  was  above  the  cover, 
whilst  the  bulb  was  in  the  acid  mixture.  Below  the  nitrator  a  large  tank 
was  provided  containing  water  into  which  the  charge  could  be  run  if  the 
temperature  rose  beyond  control.  On  completion  of  the  nitration  the  whole 
of  the  charge  of  waste  acids  and  n  it to  -glycerine  Mas  run  slowly  into  a  large 
tank  of  water,  which  was  kept  in  agitation  by  means  of  wooden  paddles  operated 
by  hand  or  mechanically.  The  nitro-glycerine  was  allowed  to  separate  out 
at  the  bottom  of  this  tank,  and  was  then  drawn  off  into  smaller  vats  and 
washed  several  times  with  soda  solution  and  water  until  neutral. 

This  system  involved  the  loss  of  the  whole  of  the  waste  acids,  and  if  the 
rate  of  flow  into  the  water  was  not  controlled  very  carefully,  a  dangerous 
amount  of  heating  was  liable  to  occur.  In  any  case  much  nitrous  fume  was 
formed  and  there  was  some  loss  of  nitro-glycerine  through  decomposition. 
For  these  reasons  the  separating  tank  was  introduced  towards  the  end  of  the 
'seventies.  The  charge  was  run  into  this  through  a  cock  at  the  bottom  of 
the  nitrator,  and  the  nitro-glycerine  being  lighter  than  the  acids  separated 
out  at  the  top,  and  Mas  transferred  to  the  washing  tank. 

In  America  iron  nitrators  are  still  used.  These  have  double  Malls,  within  Modern  plant 
which  cold  Mater  circulates,  and  are  provided  with  mechanical  agitators  instead 
of,  or  in  addition  to,  compressed  air.  In  Europe,  however,  such  plant  has 
long  ago  been  superseded  by  leaden  vessels  in  which  the  liquids  are  agitated  by 
jets  of  air.  The  Mater  before  being  passed  through  the  coils  is  generally 
cooled  by  means  of  refrigerating  plant  to  a  temperature  only  a  feM'  degrees  above 
its  freezing-point.  This  enables  the  nitration  to  be  carried  out  more  rapidly 
and  at  a  loM'er  temperature.  The  outer  water  jacket  has  been  done  away 
with.  The  nitrator  has  frequently  been  made  in  the  form  of  a  wooden  tank 
lined  with  lead,  but  the  best  modern  practice  is  to  construct  it  of  lead  only, 
sheet  being  used  of  sufficient  thickness  to  stand  without  support. 

The  form  that  the  nitro-glycerine  plant  had  generally  assumed  by  the 
end  of  the  nineteenth  century  may  be  seen  from  the  diagram  of  the  factory 
that  was  erected  at  Waltham  Abbey  in  1890  (Fig.  39).  The  nitrator  Mas  of  Nitrator. 
the  form  that  has  just  been  described.  The  top  consisted  of  a  dome  of  lead, 
which  Mas  cemented  on  and  provided  with  glass  inspection  windows.  The 
air  pipes,  the  pipe  for  the  mixed  acids,  and  the  inlet  and  outlet  pipes  for  the 
cold  Mater  coils  all  passed  through  holes  in  the  cover  ;  in  the  centre  of  the 
cover  was  a  man -lid  with  an  acid  lute,  and  in  the  centre  of  that  again  Mras 
a  hole  for  the  insertion  of  the  glycerine  injector.  This  hole  was  closed  by  a 
loose  lead  plug  when  the  inject  or  was  removed.  The  air  used  for  the  agitation 
was  allowed  to  escape  through  a  fume-pipe  fitted  with  a  glass  cylinder  to  enable 
the  man  in  charge  to  observe  whether  red  fumes  Mere  being  developed.     The 


208 


EXPLOSIVES 


bottom  of  the  tank  was  provided  with  two  earthenware  cocks,  both  of  which 
were  available  if  it  should  he  necessary  to  drown  the  charge  ;  one  of  them  was 
used  f'»r  running  tin-  contents  of  tin-  nitrator  into  the  separating  tank  through 
a  movable  lead  bend. 

The  mixed  acids  having  been  run  into  the  nitrator  the  glycerine  injector 
introduced  through  the  hole  in  the  man-lid,  and  the  glycerine  was  sprayed 
}>v  means  of  air  pressure  under  the  surface  of  the  acid.  During  nitration  cold 
water  was  passed  through  the  coils,  and  the  contents  of  the  nitrator  were 
kept  in  a  state  of  violent  agitation  by  means  of  numerous  jets  of  compressed 
air.  The  inflow  of  glycerine  was  regulated  bo  as  to  keep  the  temperature  of 
the  charge  at  or  below  22    C.     When  all  the  glycerine  had  been  added,  the 


Ar 
w  \    Waste  add  Unk. 
AJJ.  AfU  r  .-•  jiaratine 
DOti 


Xitrati:  . 


Serarating  boose 


MA.  Mix- 'I  acid  tank. 

Q.  Glycerine  tank. 

X.  Nitrator. 
D.T.  Drowning  tank. 


8    --jarator. 
tank. 
D.T.  Drowning  tank. 
P.w.  Pre-wasfa  tank. 


W.T.  Washing  tank. 
D.T.  Drowning  tank 


Washing  house      Weighing  ami 

mixing  house 
F.T.  Filt.r  tank. 


Wash  water 

-•  ttling  house 
\v.\v.?.  Wash  water 
•  ling 
tank. 


Fig.  39.     Diagram  of  Old  Nitro-glycearine  Plant  at  Walt  ham  Abbey. 


Injector. 


injector  was  removed,  the  charge  cooled  down  to  about  1 5  .  and  then  run 
off  into  the  separator.  h\  factories  where  refrigerated  water  is  not  available 
it  is  not  always  possible  to  nitrate  at  such  a  low  temperature  :  the  German 
official  regulations  lay  down  that  the  temperature  shall  never  exceed  30  . 
and  the  charge  must  not  be  run  into  the  separator  until  it  has  been  reduced 
to  25  . 

For  introducing  the  glycerine  into  the  acids  an  ingenious  form  of  injector 
was  used  by  Nobel,  and  was  adopted  in  many  factories.  Tt  consists  of  two 
metal  tubes  one  within  the  other  ;  the  outer  one  is  for  the  glycerine,  and  the 
inner  one  for  compressed  air.  and  there  are  two  flexible  diaphragms  bo  arranged 
that  if  the  air  pressure  fail,  or  if  it  rise  too  high,  the  supply  of  glycerine  is  cut 


MANUFACTURE   OF  NITROGLYCERINE  209 

off.  The  air  carries  the  glycerine  in  the  form  of  a  fine  spray  into  the  mixed 
acids.  Formerly  this  appliance  was  made  of  iron,  but  it  is  now  generally  built 
of  aluminium.  Its  one  disadvantage  is  that  it  requires  constant  attention  to 
keep  it  in  good  working  order,  and  for  this  reason  many  prefer  to  use  a  simpler 
appliance  consisting  merely  of  a  rose  of  lead  or  aluminium  having  a  large 
number  of  holes.  Through  this  the  glycerine  is  forced  from  a  closed  tank, 
by  means  of  air  pressure,  and  falls  as  a  fine  rain  on  the  surface  of  the  acid, 
with  which  the  globules  are  caused  to  mix  at  once  by  the  violent  agitation. 

At  Waltham  Abbey  the  separator  was  situated  in  the  same  building  as  Separator, 
the  nitrator  and  the  preliminary  washing  tank,  but  in  many  other  factories 
the  nitrator  is  in  a  building  by  itself,  and  the  separator  and  preliminary  washing 
tank  in  another.  The  separator  at  Waltham  Abbey  was  a  square  lead  tank, 
the  bottom  of  which  sloped  down  from  all  four  sides  to  a  central  hole  fitted 
with  a  vertical  glass  cylinder.  A  horizontal  lead  pipe  with  branches  in  four 
directions  was  connected  to  the  lower  end  of  the  cylinder,  and  each  branch 
was  provided  with  an  earthenware  cock.  Under  the  separator  was  a  lead- 
lined  tank  for  the  purpose  of  catching  the  contents  of  the  separator  in  case 
the  glass  cylinder  should  break.  The  separator  was  provided  with  a  skeleton 
frame  cover  filled  in  with  glass,  the  sides  sloping  up  to  a  pipe  which  carried 
off  the  fumes  ;  air  pipes  were  led  into  the  separator  through  the  cover,  so 
that  if  there  should  be  any  sign  of  spontaneous  heating  in  the  nitro-glycerine, 
it  could  be  stirred  up  and  mixed  again  with  the  waste  acids,  which  would 
reduce  the  temperature  once  more.  A  thermometer  passed  through  the  lid 
of  the  versel  with  its  bulb  in  the  nitro-grycerine  and  its  scale  above  the  lid, 
so  that  any  rise  of  temperature  could  be  seen  at  once.  On  the  side  of  the 
separator  there  was  a  glass  inspection  window,  also  an  earthenware  cock 
situated  about  4  inches  below  the  surface  of  the  nitro-glycerine.  When  the 
separation  was  complete,  the  bulk  of  the  nitro-glycerine  was  run  off  through 
this  cock  into  the  preliminary  washing  tank.  The  waste  acid  was  then  run 
away  through  one  of  the  branches  of  the  bottom  pipe  to  the  "  after-separating 
house."  As  soon  as  the  rest  of  the  nitro-glycerine  was  seen  coming  down 
into  the  glass  cylinder,  the  cock  leading  to  the  after-separating  house  was 
closed,  and  the  one  leading  to  the  "pre-wash  "  tank  was  opened,  and  the 
remainder  of  the  nitro-glycerine  run  into  this  tank.  Of  the  other  two  cocks 
at  the  bottom  of  the  separator  one  was  used  for  running  to  the  "  wash-water 
settling  house  "  any  thick  sludge,  that  separated  at  the  surface  dividing  the 
acid  from  the  nitro-glycerine,  and  the  other  was  connected  to  the  drowning  tank. 

In  some  factories  an  open  separator  was  used  instead  of  a  closed  tank, 
and  the  nitro-glycerine  as  it  separated  was  removed  by  hand  with  a  metal 
skimmer,  generally  of  aluminium,  and  transferred  little  by  little  to  the  pre- 
wash  tank. 

Pr6~w<ish 

The  old  pattern  of  preliminary  washing  tank,  usually  called  the  "  pre-  tank. 
vol.  i.  14 


210 


EXPLOSIVES 


Wash-waters 


wash  tank.'"  was  fitted  with  two  earthenware  cocks,  an  upper  one  for  running 
off  the  washing  waters,  and  the  lower  one  to  run  the  nitro-glycerine  to  the 
washing  house.  The  air  pipe  for  agitating  the  charge  was  laid  Loosely  on 
the  bottom  ;  another  pipe  was  led  into  the  bottom  faucet  down  the  inside 
of  the  tank  ;  the  tank  was  open  at  the  top.  The  object  of  " pre-washing  " 
is  to  remove  the  bulk  of  the  acid  from  the  uitro-glycerine  as  tpiickh  -  ssible, 
and  render  it  almost  neutral  before  it  i>  sent  down  to  the  washing  hi 
To  do  tin-  it  is  agitated  for  a  few  minutes  with  about  four  different  lots  of 
wash-water  and  then  with  a  weak  solution  of  sodium  carbonate. 

The  washing  tank  was  >innlar  to  this  and  was  provided  with  cocks,  one 
at  the  bottom  for  running  or!  the  nitre-glycerine,  and  one  or  more  skimming 
cocks  at  different  levels.  An  alternative  arrangement  for  running  off  the 
wash-water  was  a  skimmer,  a  Baucer-shaped  funnel  attached  to  a  rubber 
pipe,  which  led  through  the  side  of  the  tank  to  the  wash-water  gutter.  The 
early  form  of  skimmer  was  of  lead  supported  by  means  of  a  rope  and  counter 
weight.  Later  patterns  were  made  of  lighter  material,  such  a-  brass  covered 
with  rubber  cloth. 

The  filtration  of  the  washed  nitro-glycerine  is  generally  carried  out  in 
the  washing  house  in  a  leaden  tank.  Formerly  it  was  filtered  through  dry. 
coarse-grained  salt  contained  in  a  flannel  bag  supported  on  wire  gauze.  The 
greater  part  of  the  water  in  suspension  in  the  nitro-glycerine  was  absorbed 
by  the  salt,  whilst  the  nitro-glycerine  flowed  into  the  tank.  This  had  an 
earthenware  cock  by  means  of  which  the  nitro-glycerine  was  run  into  a  rubber 
bucket  standing  on  the  pan  of  a  pair  of  scales,  so  that  the  correct  quantity 
could  be  weighed  out  for  a  charge  of  the  explosive  that  was  to  be  made.  At 
the  end  of  the  day's  work,  or  oftener  if  necessary,  the  salt  bag  was  renewed. 
and  the  salt  was  dissolved  in  warm  water  to  recover  any  nitro-glycerine  it 
might  contain. 

The  filtration  is  now  carried  out  at  Waltham  Abbey  not  in  the  washing 
but  in  the  mixing  houses.  The  nitro-glycerine  rims  down  a  gutter  to  the 
mixing  house,  and  from  there  into  a  plain  lead  tank  with  a  false  bottom  of 
perforated  lead,  on  which  lies  a  layer  of  sponges  sewn  up  in  flannel.  The 
nitroglycerine  filters  through  the  sponges,  which  retain  the  moisture  and 
tlocculent  matter.  The  nitroglycerine  is  drawn  off  from  the  tank  by  means 
of  a  rubber  tube,  through  which  it  flows  to  the  measuring  v-  — .  •■•  , 
which  is  placed  just   below  it. 

All  the  waters  used  for  washing  the  nitro-glycerine  and  plant  are  run  down 
lead  gutters  into  a  large  tank  in  the  "  wash-water  settling  house,"  and  the 
contents  of  the  tank  are  kept  agitated  by  means  of  compressed  air.  At  the 
end  of  the  day's  work  the  air  i-  shut  off  and  any  nitro-glycerine  is  allowed 
to  settle  out.  This  is  drawn  off  from  the  bottom  of  the  tank  and  returned 
to  the  pre-wash   tank.     The   residual   mud   consists  mostly  of  lead  sulphate 


MANUFACTURE    OF  NITROGLYCERINE  211 

mixed  with  water  and  nitro-glycerine  and  some  Band,  wool,  etc.  It  is  rendered 
alkaline  with  soda  solution,  and  filtered  and  washed  with  warm  water  in  the 
"mud  hut."  This  converts  most  of  the  lead  sulphate  into  carbonate,  and 
renders  the  material  much  Less  dangerous.  The  mud  is  subsequently  wrung 
out  in  flannel  to  remove  us  much  nitro-glycerine  as  possible,  and  finally  it 
is  mixed  with  kerosine  and  burnt.  At  Walt  ham  Abbey  the  wash-waters  are 
finally  run  into  a  small  pond,  in  which  a  couple  of  dynamite  cartridges  are 
exploded  every  week  so  as  to  destroy  any  nitro-glycerine  that  may  still  be 
present. 

The  waste  acid  from  the  separator  carries  with  it  some  nitro-glycerine,  After-sepan 
which  is  present  in  it  in  three  forms  :  there  are  some  minute  globules,  which  tion" 
have  not  had  time  to  separate  out  completely,  there  is  some  in  solution  in 
the  acids,  and  there  is  some,  which  may  be  called  "  potential  nitro-glycerine," 
which  has  not  actually  been  formed,  but  is  present  as  mono-  and  di-nitro- 
glycerine,  and  may  be  converted  into  tri -nitro-glycerine  on  standing,  so  causing 
a  further  separation  at  the  surface  of  the  acids.  In  order  to  avoid  the  great 
danger  that  would  be  caused  by  the  separation  of  nitro-glycerine  in  any  part 
of  the  acid  plant,  the  waste  acid  is  generally  allowed  to  stand  first  for  several 
days  in  an  "  after-separator  "  (German  :  "  Nachscheider  ").  This  consists 
of  a  large  cylindrical  lead  tank  with  a  conical  top  surmounted  by  a  glass  cylinder. 
It  is  filled  until  the  surface  of  the  liquid  is  visible  inside  the  glass.  Any  nitro- 
glycerine that  separates  is  removed  by  the  attendant  with  a  small  aluminium 
scoop,  and  washed  with  water  in  a  small  lead  tank,  and  then  carried  over 
by  hand  in  a  rubber  bucket  to  the  washing  house.  The  after-separating 
house  contains  a  number  of  after-separators  so  that  it  can  hold  several  days' 
supply  of  waste  acid. 

During  the  first  years  of  the  present  century  a  number  of  important  im-  Recent  im" 

Drove  merits 

provements  were  introduced  at  the  Royal  Gunpowder  Factory,  Waltham 
Abbey,  into  the  methods  of  manufacturing  nitro-glycerine,  as  also  into  the 
other  processes  carried  out  there.  Those  relating  to  the  manufacture  of 
gun-cotton  have  been  mentioned  in  Chapters  XII  and  XIII.  Major  (now 
Lt.-Col.  Sir)  F.  L.  Nathan  was  the  Superintendent,  and  Mr.  J.  M.  Thomson 
the  Manager,  and  the  nitro-glycerine  plant  was  under  the  charge  of  Mr.  W. 
Rintoul.  The  far-reaching  alterations  have  been  dealt  with  by  the  first  two 
named  of  these  in  the  Journal  of  the  Society  of  Chemical  Industry,  1908,  p.  193. 

The  operation  of  washing  the  nitro-glycerine  would  appear  to  be  a  compara-  washing, 
tively  safe  one  as  the  material  is  neutral  or  alkaline,  and  it  is  only  subjected 
to  agitation  by  means  of  compressed  air  ;  yet  there  have  been  a  considerable 
number  of  fatal  accidents  in  washing  houses.  H.M.  Chief  Inspector  of  Explo- 
sives in  his  Special  Report  No.  162  on  the  explosion  at  Faversham  on  November 
9,  1903,  gives  a  fist  of  nine,  which  had  occurred  in  Great  Britain  alone,  and 
there  was  another  one  at  Havle  on  January  o,  1904  (Special  Report  No.  164),  as 


212  EXPLOSIVES 

well  as  a  considerable  number  in  other  countries      0      possibk  >f  some  of 

htastrophi  3  was  f  of   the  loose  air-pipe,  which  was  simply 

laid  on  the  bottom  of  the  tank  :    it  is  quite  conceivable  that  the  jarrii  _ 
tins  pipe  on  to  the  bottom  of  the  tank  illicit  in  exceptional  circumsl 

se  an  explosion.     The  air-pipe  is  krried  down  the  outside  of  the 

tank  from  above  the  level  of  the  liquid  and  is  burnt  on  to  the  under  surface 

of  the  bottom  of  the  tank.     B     es  erced  through  at  intervals,  and  there 

hole  in  the  end  of  each  branch  of  the  air-pipe  so  arranged  that  any  nitro- 

rine.  that  has  lodged  in  the  pipe,  will  be  blown  out  again  into  a  shallow 

depression  which   -         -  down  to  the  nutlet. 

The  wooden  casing  of  the  washing  tank-  has  ale  done  away  with. 

It  was  always       se     le  that  a  small  leak  might  be  formed  through  which  nitro- 
glycerine would  pass  and  soak  into  the  wood  and  tl  '   up  a  dangerous 
decomposition,  and  mtro-glvcerine  was  always  liable        _■  I   spilt  or 
on  to  the  wood. 

Another  possible  -  of  danger  was  the  presence  of  tin-  nu 

through  which  the  nitro-glycerine  had  to  pass.      Friction   might   be 
if  the  cock  stuck,  or  if  the  nitroglycerine  froze  in  or  around  it  :    also  if  the 
hole  through  the  key  of  the  cock  w  straight,  there  might 

pocket  in  which  nitro-glycerine  could  lodge  and  set  up  decomposition.     Soft 
rubber  tubing  has  now  been  substituted  for  the  cocks,  arranged  as  is  shown 
in  Y ._     -       which,  however,  still  shows  a  wooden  casing  to  the  tank.     The 
rubber  tube.  <7.  is  fu  i  the  outlet  lead  pipe,  and  is  kept  closed  by 

supping  it  over  the  hollow  lead  plug,  e,  through  which  a  small  current  of  air  is 

ssed  whilst  the  mtro-glvcerine  is  being  washed.     When  the  charge  is  n 
to  be  run  off,  the  air  is  shut  down,  and  the  rubber  tube  kinked  in  the  hand 
and  pulled  off  the  plug.     The  flow  of  the  nitro-glycerine  can  be  controlled 
_  the  tube  with  the  hand.     The  skimming  c,  is  al>o  of  soft 

rubber  ;  the  hard  and  heavy  skimmer  has  been  done  away  with.  This  skim- 
ming tube  has  since  been  improved  by  widening  it  at  the  mouth  funnel-wise 
and  providing  it  with  a  rubber  handle. 

It  has  __         1  that  the  explosions  in  washing  tank-  may  have 

d  by  the  generation  of  electricity  by  the  friction  of  the  air  when  passing 
through  the  jets  in  the  air-pipes.  But  air  or  other  gas  cannot  produce  elec- 
tricity by  fri  •  -  -  Bhown  by  Faraday.1  It  is  only  when  the  air  carries 
with  it  parti  lid  matter  or  liquid  globules  that  any  charge  is  formed, 
and  then  only  if  the  solid  or  liquid  matter  be  itself  non-conducting.  The 
nitro-glycerine  is  surrounded  on  all  sides  by  conductors  :  on  its  upper  surface 
ion.  and  everywhere  else  by  lead,  so  that  any  charge  would  be 
rapidly  discharged,  especially  as  the  nitroglycerine  is  kept  in  motion  and  is 

1   "Experimental  -  Will..  PhU  January 

1843. 


Fig.  40.     Nitro -glycerine  Washing  Tank 

„    Air-pipe  '•  Skinxming  tube  for  wash-waters 

,/,  Out  lit    pipe  for  nitro-glycerine  '•   Hollow  lead  plug  for  end  of  (/ 

//,  Holes  in  ends  of  branches  of  air-pipe 


214 


EXPLOSIVES 


mixed  with  drops  of  the  soda  solution.     Experiments   carried  out  at  Ardeer 
failed  to  detect  any  charge  of  electricity.1 

The  pre-wash  tank  u  structed  in  the  same  way  as  the  final  washing 
tank  :  the  principal  difference  lies  in  the  arrangements  made  for  conducting 
away  the  fumes.  The  air  rising  from  the  pre-wash  tank  carries  some  nitric 
acid  with  it  as  well  as  fume-  of  the  nitric  esters  of  glycerine  :  the  tank 
a  fixed  lead  cover  with  an  opening,  which  i-  kept  covered  with  a  small  rubber 
flap,  and  there  is  a  fume  pipe  through  winch  the  fumes  are  drawn  by  means 
of  a  jet  of  air  or  .-team.  From  the  washing  tank  the  air  carries  away  only 
vapour  of  water  and  mtro-glvcerine..  consequently  the  lead  top  is  unnecessary  : 
it  is  merely  provided  with  a  hood  of  rubber  cloth  shaped  like  a  large  inverted 
funnel,  the  stem  of  winch  pas:-es  out  through  the  roof  and  is  provided  with 
an  air  jet  to  keep  a  current  of  air  going  in  an  upward  direction  during  the 
whole  of  the  time  of  the  washing.  The  removal  of  the  fumes  of  nitro-glycerine 
make>  the  work  much  less  trying  to  the  workmen.  In  the  pre-wash  tank  the 
air-holes  in  the  bottom  are  bushed  with  small  perforated  ebonite  plugs 
prevent  the  rapid  enlargement  of  the  holes,  but  in  the  final  washing  tanks 
-mall  plug-  are  mmecesfi  -  the  wear  is  very  slow. 

A  very  hard  stony  deposit  consisting  mostly  of  calcium  carbonate  used 
formed  on  the  inside  surface  of  the  washing  tank,  due  to  the  action  of 
the  >oda  solution  on  the  hard  water  employed.     This  was  another  possible 
source  of  danger.     The  formation  is  now  prevented  filing  the  water 

There  is  a  large  tank  in  the  charge  house  above  the  level  of  the 
nitrating  house,  and  in  this  sufficient  water  is  treated  each  day  to  suffice  for 
all  the  washing  operations  of  the  next  day.  Enough  lime  and  sodium  car- 
bonate is  added  to  precipitate  the  bicarbonate  and  sulphate  of  calcium  and 
the  magnesia,  and  the  water  is  well  agitated  and  allowed  to  :>ettle  over  night. 

Washing  tank-  should  be  made  wide  and  shallow.,  because  a  reduction  in 
the  depth  of  the  liquid  greatly  diminishes  the  time  required  for  the  separation 
of  the  nil       _      erine  from  the  water.     At  the  Royal  I  ler  Fa 

comparative  trials  were  carried  out  with  two  different  designs  of  tank.,  the 
proportion  of  water  to  nitro-glycerine  and  all  other  conditions  being  kept 
ant.     The  depth  of  liquid  only  was  varied  by  having  the  tanks  of  different 
diameters.     The  result-  were  : 


Total  depth  of  liquid 
27*  in. 
18i  in. 


time  of  separation 
.      34      28     - 

.      1".       M     .. 


In  the  pre-wash  tank  the  nitro-glycerine  is  usually  washed  about  four  times 
tore  of  about  18°C.    The  first  three       -      gs  are  with  water  only, 

but  the  last  with  some  aoda,  -       si  •    all  but  a  >mall  quantity  of  the 

acid.     The  nitro-glycerine  is  then  sent  down  a  gutter  to  the  washing 

.  8. 


MANUFACTURE   OF  NITROGLYCERINE  215 

where  the  final  washing  is  carried  out.  The  number  and  duration  of  the 
washings  vary  considerably  in  different  works,  but  the  following  scheme  is 
a  good  one : 

1st  washing  15  minutes  with  dilute  soda  (3i  per  cent.  NaiC08) 

-net         ,,  60  ,,  ,,  ,,  ,,  ,,  , 

olCl  ,,  'to  , ,  ,,  ,,  , ,  , ,  , , 

4th         ,,  15  „     with  softened  water  only 

otn         ,,  lo  ,,  ,,  ,,  ,, 

Temperature  of  washing  30°  C,  proportion  of  soda  solution  or  water  to  nitro- 
glycerine 4  :   10  by  weight. 

All  the  wash-waters  from  the  pre-wash  and  final  washing  tanks  are  run  Labyrinths 
through  labyrinths  before  they  pass  to  the  wash-water  settling  tank,  and  from 
the  latter  they  again  pass  through  a  labyrinth  before  they  reach  the  pond. 
The  labyrinth  consists  of  a  long  lead  tank  ojDen  at  the  top  and  provided  with 
a  number  of  transverse  partitions  so  arranged  that  the  water  has  to  flow 
alternately  over  one  and  under  the  next.  The  bottom  is  inclined  gently  to 
a  central  channel,  which  runs  the  whole  length  of  the  vessel ;  there  is  also 
a  fall  towards  the  exit  end.  Most  of  the  globules  of  nitro-glycerine  collect 
in  this  central  channel,  and  can  be  drawn  off  through  a  rubber  tube  arranged 
in  the  same  way  as  the  delivery  tube  of  the  washing  tank.  Since  the  introduc- 
tion of  these  labyrinths  at  Waltham  Abbey  the  amount  of  nitro-glycerine 
that  is  recoverable  from  the  wash- water  settling  tank  is  only  H  per  cent., 
whereas  formerly  it  was  about  4|  per  cent. 

In  those  parts  of  the  plant  where  the  nitro-glycerine  is  mixed  with  strong  Nitrator- 
acid.  i.e.  the  nitrator  and  separator,  it  is  not  possible  to  make  use  of  delivery  seParator- 
tubes  of  rubber,  such  as  have  been  substituted  for  cocks  in  all  other  parts  of 
the  mtro-glycerine  plant.  Yet  cocks  are  specially  dangerous  here  as  the 
acid  nitro-glycerine  is  more  liable  to  spontaneous  decomposition  than  when 
it  is  neutral  or  slightly  alkaline.  In  January  1901,  this  danger  was  brought 
home  at  the  Royal  Gunpowder  Factory  in  a  very  forcible  manner  :  shortly 
after  the  charge  had  been  run  out  of  the  nitrating  apparatus  an  explosion 
occurred  in  one  of  the  earthenware  cocks  leading  to  the  drowning  tank.  If 
the  apparatus  had  contained  the  charge,  a  serious  accident  must  inevitably 
have  occurred.  This  led  to  the  idea  of  removing  the  nitro-glycerine  at  the 
top  of  the  nitrator  instead  of  at  the  bottom  ;  a  method  the  accomplishment 
of  which  was  rendered  more  easy  by  the  fact  that  the  nitro-glycerine  separates 
out  at  the  top  of  the  charge.  The  simplest  way  to  effect  this  was  to  raise 
the  whole  of  the  contents  of  the  apparatus,  so  that  the  nitro-glycerine  would 
flow  over  a  suitable  arrangement  in  the  cover  and  run  by  gravity  into  the 
pre-wash  tank,  and  the  best  method  for  raising  the  level  was  to  introduce 
waste  acid  from  a  previous  charge  at  the  bottom  of  the  vessel. 


216 


EXPLOSIVES 


The  form  of  plant  adopted  to  carry  out  this  principle  is  shown  in  Fig.  41, 
and  is  protected  by  English  Patent  No.  15,983,  dated  August  B,  L901,  taken 
out  in  the  joint  names  of  Nathan,  Thomson,  and  Rintoul.  The  separation 
of  the  nitro-glycerine  from  the  acids  takes  place  in  the  same  vessel  as  the 
nitration,  and  for  this  reason  the  inventors  call  it  a  "  nitrator-separator.'1 
It  consists  of  a  cylindrical  lead  vessel,  a.  with  a  bottom  sloping  in  one  direction, 
and  containing  cooling  coils  and  air-pipes,  the  number  of  which  depends  on 
the  size  of  the  vessel.  The  cooling  coils  enter  and  leave  through  the  sides 
just  below  the  surface  of  the  nitrating  acid,  as  also  do  the  air-pipes,  g.  The 
cooling  water  is  led  in  and  out  again  through  one  main  pipe  controlled  by 
a  -ingle  cock,  and  the  coils,  //.  branch  away  from  this  main  pipe  inside  the 
asel.  The  supports  for  the  coils  are  of  lead,  and  are  formed  by  loading 
up  between  the  turns  ;  this  arrangement  obviates  the  use  of  lead-covered 
iron  supports,  and  entirely  does  away  with  interstices  in  which  nitro-glycerine 
or  sulphate  can  lodge.  The  cover  is  conical,  and  is  burnt  on  to  the  cylindrical 
portion  :  it  terminates  in  a  cylinder,  e,  of  small  diameter  open  at  the  top  and 
provided  with  glass  inspection  windows.  /  ;  the  only  other  fitting  in  the  cover 
is  a  gland,  through  which  the  thermometer,  s,  passes.  A  pipe,  k,  opens  out 
of  one  side  of  the  cylinder,  and  from  this  another  pipe.  m.  branches  for  carrying 
away  the  fumes,  suction  being  produced  by  means  of  an  air-jet.  At  a  little 
distance  beyond  this  fume  pipe  k  opens  out  to  a  gutter  leading  down  at  an 
incline  to  the  pre-wash  tank.  The  pipe,  d.  for  introducing  the  mixed  acid 
into  the  apparatus,  as  well  as  the  waste  acid  for  the  displacement,  enters  the 
vessel  at  the  bottom.  In  order  to  prevent  any  nitro-glycerine  getting  into 
the  acid  supply  pipe  it  is  carried  vertically  downwards  below  the  bottom  of 
the  vessel  and  rises  again  into  it.  There  are  two  branches.  &,  c,  leading  out 
of  this  pipe,  each  with  an  earthenware  cock  ;  h  leads  to  the  waste-acid  egg, 
and  c  to  the  drowning  tank. 

The  waste  acid  from  the  previous  charge  having  been  run  out  of  the  \  i 
the  cock  on  the  nitrating-acid  tank  is  opened,  and  the  acid  is  allowed  to  run 
into  the  nitrator-separator  by  opening  the  cock  on  the  acid  supply  pipe.  (/. 
As  soon  a>  the  acid  has  all  run  in,  the  cock  on  the  nitrating-acid  tank  is  closed 
as  well  as  that  on  the  acid  supply  pipe,  and  the  acid  having  been  brought  to 
the  desired  temperature  by  means  of  the  cooling  coils  the  injector  is  inserted 
through  the  open  top  of  the  apparatus,  and  the  nitration  is  commenced.  The 
temperature  of  the  cooling  water,  which  Hows  through  the  coils  is  regulated 
so  that  the  total  time  of  nitration  for  any  given  charge  is  kepi  constant  within 
fairly  narrow  limits  both  winter  and  summer.  To  enable  this  to  be  done 
the  water  is  refrigerated  when  necessary.  The  advantages  of  using  refrigerated 
water  are  that  nitration  is  completed  in  a  reasonable  time,  loss  of  nitric  acid 
due  to  volatilization  is  reduced,  and  the  time  of  nitration  being  constant  the 
operations  of  the  factory  can   be  carried  out  in  a  systematic  manner.     The 


A 


mo 


^-^ 


Fig.  41.     Nitrator-Separator  for  the  Manufacture  of  Nitro -glycerine  (from  SS  ) 

217 


218  EXPLOSIVES 

volatilized  nitric  acid  is  carried  away  to  a  Guttmann  condensing  tower  pro- 
vided with  a  circulating  arrangement  for  the  liquid  ;  the  fames  arc  thus  con- 
densed and  about  181b.  of  nitric  acid  of  specific  gravity  1  -32  are  recovered  per 

ton  of  nitro-glycerine  produced.  When  nitration  is  completed,  the  injector  is 
removed,  and  the  nitro-glycerine  is  allowed  to  separate  for  a  few  minutes. 
The  cock  leading  from  the  displacement  ua>te-aeid  tank  is  then  opened,  and 
waste  acid  is  allowed  to  enter  the  apparatus  at  the  bottom  by  opening  the  acid 
supply  pipe  The  rate  of  inflow  of  the  displacing  acid  can  be  regulated  with 
the  utmost  nicety,  so  as  to  allow  of  the  nitro-glycerine  flowing  over  through 
the  gutter  to  the  pre-wash  tank  as  it  separates.  The  dividing  line  between  the 
clear  nitro-glycerine  and  the  acid  is  watched  through  the  inspection  window-. 

The  nitrator-separator  is  left  full  of  waste  acid  until  it  is  required  for  the 
nitration  of  another  charge.  The  result  of  this  is  that  no  part  of  the  interior 
of  the  apparatus  is  exposed  to  acid  fumes,  and  its  life  is  greatly  increased. 
In  the  old  form  of  plant,  in  which  this  could  not  be  done,  and  the  coils  entered 
through  the  cover,  it  was  necessary  to  remove  the  cover  and  the  coils  as  often 
as  once  in  every  three  months  to  repair  them.  The  new  form  of  apparatus 
\\a>  in  use  for  two  and  a  quarter  years  without  being  opened  up,  and  then 
the  whole  of  the  interior  including  the  coils  and  air-pipes  were  found  to  be  as 
good  as  new .  and  no  repairs  of  any  kind  were  required.  As  a  precaution  the 
cooling  coils  are  tested  every  week  by  air  pressure  before  commencing  work  : 
any  leak  would  be  detected  at  once  by  the  escape  of  air  bubbles  through  the 
waste  acid. 

It  is  well  to  arrange  the  exit  pipe  from  the  coils  so  that  the  water  in  them 
is  under  a  slight  vacuum.  If  a  small  leak  does  develop,  the  acid  will  then 
enter  the  coils  where  it  will  be  drowned  by  the  large  volume  of  water,  and 
the  defect  will  be  shown  by  a  rise  in  the  temperature  of  the  water  leaving 
the  coils.  In  Germany  several  explosions  have  been  ascribed  to  the  bursting 
of  the  coils,  but  no  such  accidents  appear  to  have  occurred  in  England.  It 
has  been  proposed  by  the  Explosive  Works,  Dr.  R.  Nahnsen  and  Co.  of  Ham- 
burg, to  use  chloroform,  carbon  tetrachloride,  or  other  similar  chlorine  deriva- 
tives for  circulating  through  the  coils,1  but  this  does  not  appear  to  be  necessary 
provided  that  reasonable  precautions  are  taken. 

The  after-separating  house  has  for  some  time  ceased  to  exist  at  the  Royal 
Gunpowder  Factory.  Its  abolition  was  rendered  possible  by  the  fact  that 
the  addition  of  water  to  the  waste  acid  not  only  prevents  the  formation  of 
more  nitro-glycerine,  but  also  absorbs  any  that  exists  as  minute  globules 
in  the  waste  acid.2  Originally  only  2  per  cent,  of  water  was  added  to  the 
waste  acid,  as  this  quantity  was  found  to  be  sufficient  at  the  normal  tempera- 
ture of  storage,  10°  to  15°  C.,  to  prevent   any  further  separation.     But  on 

1  Got.  Pttt.  Anui.  31,837,  Julj    6,    1910;    8.S.,   1912,  p.  36. 

-  Nathan,  Thomson  and   Rintoul,   Eng.   Pat.  3020,   February  9,    1903. 


MANUFACTURE   OF  NITRO-GLYCERINE 


219 


January  15,  1906,  a  fatal  accident  occurred  with  a  drum  of  nitro-glycerine 
waste  acid,  which  was  part  of  a  consignment  sent  by  the  Explosives  and 
Chemical  Products  Ltd.,  to  Messrs.  F.  W.  Berk  and  Co.  In  consequence  of 
this,  further  experiments  were  carried  out  at  Waltham  Abbey,  which  are 
given  in  detail  in  Special  Report  No.  174  of  H.M.  Chief  Inspector  of  Explo- 


JL^ 


WATER    TANK 


s>T0  WASTC   ACID  ECCS 

Fig.  42.     Waltham  Abbey  Nitrating- Ho  use  Plant 


sives.  It  was  then  found  that  in  order  to  prevent  further  separation  of  nitro- 
glycerine, when  the  temperature  of  the  waste  acid  is  reduced  to  0°  C.  it  is 
necessary  to  add  5  per  cent,  of  water.  The  fact  that  when  the  temperature 
is  reduced  the  solubility  of  nitro-glycerine  in  waste  acid  is  considerably  dimin- 
ished should  be  kept  constantly  in  mind.  In  Germany,  where  large  variations 
of  temperature  are  more  liable  to  occur  than  in  England,  there  have  been 
several  accidents  due  to  the  further  formation  of  nitro-glycerine  on  the  surface 
of  acid  that  had  been  subjected  to  after-separation  for  a  considerable  time. 
However  the  waste  acids  arc  treated,  they  should  not  afterwards  be  allowed 
to  fall  to  a  very  low  temperature,  and  1  lie-  denitration  should  take  place  as 


22n 


EXPLOSIVES 


sooi:  -ible.     If  after-separation  has  taken  place  without  the  addition 

of  water,  the  acid  should  afterward-  be  kept  at  a  higher  temperature  than 
that  at  which  the  after-separation  was  effected. 

The  method  adopted  for  dealing  with  the  icklfl  in  the  nitrator 

rator  i-  as  f<>ll«»w>  :  The  waste  acid  i-  allowed  t<»  remain  in  the  vessel  until 

quired  f<»r  another  nitration,  any  nitro-gl  rating  in  the  interval 

being  displaced  in  the  usual  way  into  the  pie-wash  tank.     Further  separation 
i-  promoted  by  cooling  down  the  waste  acid.     When  the  nitrator  is  to  be 


Charge  House 

MA     M 

Tank 
DJL  Displacing 

Acid  Tank 
E-  Egg 


Nitrating  House 

ycerine  Tank 
Nitrator  Separator 
D.T.  Drowning  Tank 
P.W.  Pre-wasfa  Tank 
L.  Labyrinth 


-  hfng  House 

W.T.  Washing  Tank 

L.  Labyrinth 
D.T.  Drowning  Tank 


Filtering  and  Mixing 

FT.  Filter  Tank 
B.  Burette 


W.W.S.  Wash  Water  Settling- 
I  nk 


Fi<;.  43.     Diagram  of  Nit  ro -glycerine  Plant  at  Walt  ham  Abbey 


emptied.  every  trace  of  nitroglycerine  is  removed  from  the  surface  of  the  acid, 
and  the  quantity  of  waste  acid  required  for  the  displacement  of  a  subsequent 
charge  is  then  run  out  of  the  nitrator  into  an  egg.  and  blown  into  the  displacing 
acid  tank  in  the  charge  hou-  T  the  remainder  <>f  the  waste  acid  in  the 
nitrator  2   per  cent,  of  water  is   then   added,  the  ts  of  the   nitrator 

being     *       _       .  _  I    ted    meanwhile  by    means    of   air.     The    waste    acid    i- 
then  sent    int<>   an  egg   and    blown  up    to  a    tank  in    the  denitrating  hi 
A-   a   further  precaution  all  waste  acid  i-  kept  at  a  temperature  <>f  al 
15 

•  '.  W  iltham  Abbey  plant  i<  shown  diagrammatically  in  F;_>   42,  4:;. 

T  advantage  of  the  plant  is  that  the  elevation  <»f  the  nitrator  above  the 
settling  tank  is  less  than  half  what  it  was  with  the  old  style  of 


MANUFACTURE   OF   NITROGLYCERINE  221 

plant,  viz.  16  feet  instead  of  33|  feet.1  The  separating  and  after-separating 
houses  are  dispensed  with,  with  the  resull  that  the  factory  occupies  less  space, 
and  there  are  fewer  pieces  of  apparatus. 

The  safety  of  the  manufacture  is  increased  by  the  absence  of  cocks,  and 

by  the  removal  of  the  nitro-glyeerine  from  contact  with  the  acid  as  soon  as 
it  has  separated  from  it.  This  is  an  especially  great  improvement  over  the 
procedure  in  the  factories  where  the  separator  is  in  a  different  house  to  the 
nitrator,  for  there  the  acid  nitro-glyeerine  has  to  How  down  a  long  gutter 
from  one  house  to  the  other.  The  presence  of  cooling  coils  during  the  separa- 
tion is  also  an  advantage.  As  fewer  men  are  required  to  work  the  plant  the 
risk  to  personnel  is  correspondingly  reduced. 

The  diminution  of  danger  during  separation  is  a  matter  of  considerable 
importance  as  there  have  been  a  number  of  disastrous  explosions  in  nitro- 
glyeerine  separators.  On  February  IS.  1904.  the  separator  at  the  Cliffe 
Factory  started  to  fume  violently  and  then  exploded,  causing  the  death  of 
four  men  and  much  structural  damage.-  At  Avigliana.  in  Italy,  a  similar 
accident  occurred  in  April  L912,  and  although  the  men  in  the  house  were  able 
to  escape  before  the  explosion,  it  caused  another  house  to  blow  up,  and  two 
men  were  thereby  killed.  In  July  1912.  a  few  days  after  the  separating  house 
had  been  rebuilt,  it  blew  up  again.  This  time  the  nitro-glyeerine  caught 
alight,  but  again  the  men  in  the  house  were  able  to  escape  before  the  remainder 
of  the  charge  exploded  ;  no  one  was  killed,  but  the  material  damage  amounted 
to  £8000.  Similar  cases  of  charges  taking  fire  in  the  separator  have  occurred 
in  Mexico.  An  explosion,  due  to  violent  decomposition  of  nitro-glyeerine 
in  a  separator,  took  place  on  March  1.  1911,  at  the  factory  at  Umbogintwini 
in  South  Africa  ;  it  was  ascribed  to  the  use  of  defective  glycerine  made  locally 
from  whale  oil.  In  1907  a  German  nitro-glyeerine  factory  was  destroyed  by 
an  explosion  originating  in  the  separator. 

The  drowning  cock  is  controlled  by  means  of  a  long  rod  terminating  in  Drowning 
a  handle  situated  on  the  operating  platform.  By  turning  this  handle  through  arrangeme 
a  quarter  of  a  circle  not  only  are  the  contents  of  the  nitrator-separator  allowed 
to  run  into  the  drowning  tank,  but  at  the  same  time  compressed  air  is  turned 
on  to  agitate  the  contents  of  the  tank,  and  water  is  also  admitted.  The  drown- 
ing tank  is  always  kept  full  of  water,  and  is  provided  with  an  overflow.  This 
drowning  arrangement  has  the  advantage  of  simplicity,  and  the  continuous 

1  It  has  been  proposed  to  reduce  the  necessary  fall  in  the  oitro-glycerine  factory 
still  further  by  causing  the  nitro-glyeerine  to  rise  from  the  bottom  of  the  washing  tanks 
through  rubber  tubes  by  the  weight  of  a  sufficiently  high  column  of  water  introduced 
above  (Wharton,  Shacklady  and  Curtis  s  and  Harvey.  Ltd..  Eng.  Pat.  23.871,  October 
14.  1010).  Messrs.  Curtis's  and  Harvey  have  erected  a  plant  with  all  the  vessels  for 
the  different  operations  in  the  same  building,  so  thai  the  separating,  washing,  filtering, 
and  measuring  of  the  nitro-glyeerine  into  1><>x(s  can  be  carried  oul  without  running  it 
down  long  gutters  to  ether  buildings.  -  Set    >./.'..   No.    107. 


a  o  o 


EXPLOSIVES 


Bupply  of  cold  water  keeps  down  the  temperature  due  to  the  mixing  of  a  large 
volume  of  acid  with  the  water,  and  also  allows  of  a  smaller  drowning  tank 
being  used  than  would  otherwise  be  necessary. 

The  regulations  of  the  German  Trade  Guild    §  Lfl    are  somewhat  similar. 

It  is  there  laid  down  that  the  drowning  tank  must  have  a  capacity  equal  to 
at  least  five  times  the  volume  of  the  acid,  and  is  to  be  provided  with  stirring 
arrangements  and  a  water  inlet  at  the  bottom  of  the  tank  of  Buch  a  size  that 
the  acid  will  be  rapidly  displaced  and  no  heating  of  the  nitro-glycerine  will  take 
place.  The  drowning  tanks  must  always  be  kept  with  the  proper  quantity  of 
water  in  them.  The  water  inlet  and  the  air  for  Btirring  must  be  turned  on  simul- 
taneously with  the  drowning  cock,  or  must  be  bo  arranged  that  they  can  be 
operated  from  a  place  of  safety  outside  the  traverse.  In  some  cases  these  cocks 
aie  so  arranged  that  they  are  all  operated  simultaneously  by  compressed  air. 
which  can  be  turned  on  from  several  points,1  but  it  is  not  advisable  to  make  such 
arrangements  too  complex,  a>  they  are  not  only  liable  to  fail,  but  through  some 
combination  of  peculiar  circumstances  they  may  act  wrongly  in  an  emergency, 
and  so  whilst  preventing  an  explosion  in  one  house,  cause  one  in  another. 

Before  oleum  could  be  obtained  at  a  reasonable  cost,  it  was  usual  to  use 
an  acid  made  by  mixing  about  5  parts  of  C.O.V.  with  3  parts  of  concentrated 
nitric  acid  (sp.  gr.  1-50).  At  Waltham  Abbey  8  parts  of  the  mixed  acid  were 
used  to  nitrate  1  of  glycerine,  but  in  some  other  works  a  smaller  amount  of  acid 
was  employed,  often  7|  parts  to  1  of  glycerine. 

Theoretically  100  parts  of  glycerine  should  give  246-7  parts  of  nitro-glycerine, 
but  for  several  reasons  this  yield  is  never  attained  in  practical  manufacture. 
The  average  yield  at  the  Royal  Gunpowder  Factory  over  a  series  of  eight  year  a 
was  -14;  percent.,  but  after  the  introduction  of  the  nitrator-separat  or  and  other 
improvements  it  was  220-2  per  cent,  as  an  average  of  two  years'  working  with 
the  proportions  just  mentioned.  There  is  practically  no  oxidation  of  the  glycer- 
ine, consequently  the  reaction  may  be  represented  by  the  following  Table  : 


Before  nitrating 

After  nitrating 

1     II    OH), 

H2S04 
UNO, 

H20 

LOO 

180 
273 

17 

I'  :  cent. 

60-0 

34  1 
5-9 

(•3H6(N03)3 

11   so, 
HX03 
H,0 

246-7 

48<"> 
105-7 

ent. 

10-3 
16-2 

1000 

53-3 

100-0) 

1  >..    U  --■  r,  SJS.,    1907,  p.  48. 


MANUFACTURE   OF   NITROGLYCERINE  223 

The  water  present   in  the  nitrating  acids  performs  no  useful  function.     It 
might  be  eliminated,  and  acid  used  as  follows  : 


Before  nitrating 

After  nitrating 

C3H5(OH)3 

H2S04 
HX03 
H20 

100 

266-6 

2420 
0 

Per  cent. 

52-3 

17-7 
0 

C?H6(N08)3 

H„S04 
HXO3 
H20 

246-7 

266-6 

:;7-:. 
58-7 

Per  cent. 

73-5 
10-3 
16-2 

500-:. 

1000 

362-8 

100-0 

But  it  is  more  usual  to  use  an  acid  containing  1  to  2  per  cent,  water.     The 
following  results  have,  for  instance,  been  recorded  by  : 


I 

Soddy 

Chalon 

Hofwimmer 

Acid  : 

H,S04  . 

58-4 

57-3 

52-5 

HXO3  . 

40-0 

41-3 

46-5 

H20 

1-6 

1-4 

10 

Proportion  Acid  : 

( ilveerine 

612,     5-88 

6-2 

6-3,     5-3 

Yield 

232,     236 

232 

228,     221 

The  results  given  by  Soddy  were  obtained  with  a  nitrator-separator  at  a 
factory  in  Mexico  ;  1  those  by  Chalon  in  a  similar  plant  in  the  dynamite  works 
of  Boceda,  in  Italy.2  Hofwimmer's  figures  were  obtained  from  laboratory 
experiments  in  which  the  proportion  of  acid  to  glycerine  was  varied  through 
a  wide  range  ;  3  the  maximum  yield  was  obtained  with  the  proportion  6-3  :  1. 
but  the  most  remunerative  proportion  at  the  prices  of  materials  assumed 
was  5-3  :  1.  At  Waltham  Abbey,  with  a  proportion  613:  1.  the  yield  for  a 
period  of  nearly  two  years  was  229  per  cent. 

The  differences  between  the  yields  generally  obtained  and  the  theoretically 
possible  yield  of  240-7  per  cent,  is  due  to  the  influence  of  various  factors.  The 
practical  yields  are  generally  calculated  upon  the  glycerine  as  nitrated,  whereas 
this  glycerine  does  not  usually  contain  more  than   97   per  cent,  of  glycerol. 


1  Arms  and  Exp.,   March   1011. 


-  Exphsifs  modernes,  1011,  p.  222. 
:!  Chem.  Z<  U.,  1011.  .v..  p.  1229.     Hofwimmer  has  given  the  results  of  further  labora. 
tory  experiments  in  S.S.,   1913,  p.  36. 


2-2i  EXPLOSIVES 

The  waste  acid  produced  on  nitration  absorbs  a  further  quantity  of  the 
nitro-glycerine.  the  proportion  absorbed  depending  upon  the  composition 
of  the  waste  acid.  A  still  further  quantity  of  the  nitro-glvcerine  disappears 
in  solution  in  the  wash  water-  from  the  pre-washing  and  washing  operations 

The  solubility  of  nil  9  rine  in  acids  of  varying  composition  formed 
the  subject  of  numerous  experiments  at  the  Royal  Gunpowder  Factory.1 
When  nitro-glvcerine  is  added  to  a  mixed  acid,  it  first  dissolves  unchanged, 
but  part  of  it  i>  at  once  decomposed  with  the  formation  of  othei  sto  -  such 
-  glycerol  trisulphate,  the  production  of  which  may  be  represented  by  the 
reversible  reaction  :    «    H-<»X<i.  :;H.s<»,    j*  CHs(SOJB       -     :\\\y<  I 

The  nitro-glvcerine  dissolved     a  a  -       termined  by  shaking  out  rapidly 

with  chloroform,  and  the  nitro-glvcerine  decomposed  wa>  estimated  by  differ- 
ence. Fig.  44  sh<  >wa  the  amount  of  nitro-glvcerine  taken  up  by  acid  containing 
water  and  nitric  acid  in  the  constant  ratio  11:1  and  varying  percentages 
of  sulphuric  acid.  It  will  be  seen  that  portions  of  the  curve-  are  represented 
by  shaded  lines.  This  indicates  that  on  attempting  to  saturate  acids  in  this 
zone  oxidation  of  the  glycerine  radicle  occurred,  and  the  results  were  vitiated. 
An  uncontrollable  reaction  would  set  in  if  special  precautions  were  not  taken  : 
no  acid  of  a  composition  in  or  near  this  zone  should  ever  be  allowed  to  come 
in  contact  with  nitro-glycerine  in  a  manufacturing  operation.  Fig.  4.5  shows 
the  results  that  were  obtained  with  acids  in  which  the  ratio  of  ""sulphuric  acid 
to  water  was  kept  constant  at  5-8  and  the  nitric  acid  was  varied.  In  Fig.  46 
the  ratio  of  sulphuric  to  nitric  acid  was  kept  constant  at  10-4,  and  the  water 
a  varied.  Fig.  47  was  obtained  with  mixtures  of  sulphuric  acid  and  water 
only  .  here  again  oxidation  took  place  with  acids  of  50  to  B5  per  cent,  strength. 
All  these  solubility  determinations  were  carried  out  at  2o  ( '.  It  will  be  seen 
that  all  the  curves  with  mixed  acids  show  a  distinct  minimum,  which  points 
to  the  fact  that  there  must  be  a  certain  composition  of  acid  which  will  be  the 

•   economical  to  use. 

The  time  that  the  nitro-glycerine  taki-  to  sej  arate  from  the  acid  is  liable 
to  vary  within  wide  limits  ;  when  the  separation  is  carried  out  in  a  special 
separator,  it  may  be  anything  from  a  quarter  of  an  hour  up  to  several  hours. 
Long  separations  are  very  inconvenient  as  they  di>organize  the  whole  of  the 
work  of  the  factory.  In  the  early  days  of  the  industry  they  were  generally 
attributed  to  impurities  in  the  glycerine,  and  probably  with  justice.  In  the 
Boutmy  system  of  manufacturing  nitro-glycerine  the  glycerine  was  dissolved 
first  in  sulphuric  acid,  the  solution  was  cooled  and  then  a  mixture  of  nitric  and 
sulphuric  acids  was  added.  But  as  a  result  of  the  action  of  the  concentrated 
sulphuric  acid  on  the  glycerine  and  the  impurities  in  it.  products  were  foil: 
which  greatly  impeded  th<  -.tion  :    no  nitro-glycerine  was  taken  off  until 

twenty-four  hours  had  elapsed,  and  then  the  adds  were  transferred  to  carl  1  ya 

han  and  Rintoul,  lo< 


MANUFACTURE   OF   NITROGLYCERINE 


225 


or  other  vessels,  where  further  separation  occurred  and  might  continue  for  a 
month.1 

Since  the  introduction  of  good  distilled  glycerine,  one  cause  of  long  separa- 


25  30  35  40  45  50   55  60  65  70  75   80  65  90  95  100 
SULPHURIC   ACID    PER  CENT 

Fig.  44 


15  20  25          30  35 

nitric    acid  per  cent 
Fig.  45 


<->  8 
bJ  7 

a. 

i» 

03 
o 


"H  D^orm 

5     6     7     8     9     10    II     12    13    14    15    i&   17    18    19  20 
WATER     PERCENT 


0    10    Z0  30  40  50   60  70  80   90  100 
SULPHURIC  ACID  PER  CENT 


Fig.  46  Fig.  47 

Figs.  44-47.     Solubilities  of  Nitro -glycerine  in  Acids 


tions  has  been  eliminated,  and  the  source  of  the  trouble  is  to  be  sought  now 

rather  in  the  acids.     A  large  amount  of  suspended  matter  in  the  acids  causes 

the  formation  of  numerous  small  drops  of  nitro-glycerine,  which  do  not  readily 

1  Fur  full  particulars  of  this  process  ami  its  disadvantages,  sec  S.B.  48,  January  1883. 

VOL.    I.  15 


226  EXPLOSIVES 

coalesce^  and  consequently  take  a  very  long  time  to  separate.     Hence  the 

important  e  of  allowing  tin-  acids  to  stand  for  Mime  days  after  mixing  in  order 
to  allow  time  for  the  insoluble  impurities  to  settle  out.     Thee  -  -t  mostly 

of  the  sulphates  of  lead,  iron  and  aluminium.  But  during  the  nitration  pn 
a  further  quantity  is  precipitated,  mostly  Lead  sulphate,  which  is  considerably 
Less  soluble  in  dilute  acids  than  in  concentrated,  and  thi>  freshly  formed  precipi- 
tate is  probably  more  injurious,  as  it  has  oot  had  time  to  be  converted  into 
larger  aggregates.  The  time  of  separation  increases  with  increase  in  the 
percentage  of  water  in  the  waste  aeid  :  this  is  no  doubt  due  partly  to  the 
larger  amount  of  lead  sulphate  precipitated,  but  may  also  be  caused  partly 
by  the  retardation  of  the  nitration  reaction  by  tin-  presence  of  the  water. 
Just  the  same  trouble  with  long  separations  i-  liable  to  occur  with  the  nitrator- 
Beparator  or  any  other  form  of  plant.  It  i<  due  to  the  formation  of  an  emulsion 
of  the  one  liquid  in  the  other,  and  is  intimately  connected  with  the  phenomena 
of  surface  tension,  but  the  matter  has  not  been  investigated  sufficiently  to 
allow  of  a  full  and  satisfactory  explanation.  The  formation  of  an  emulsion 
<an  be  prevented  by  the  addition  of  variou>  substances  to  the  charge  :  thus 
R.  Moeller.  in  Ger.  Pat.  171,106,  claimed  the  addition  of  0-05  to  0-2  per  cent. 
of  the  weight  of  glycerine  of  various  fatty  substances,  such  a-  paraffin,  vaseline, 
the  higher  fatty  acids  and  their  esters.  The  slow  separations  have  also  been 
ascribed  to  the  presence  of  silicates,  and  especially  gelatinous  silicic  acid,  and 
the  addition  of  0-001  per  cent,  of  sodium  fluoride  has  been  proposed  to  destroy 
them.1  The  Westfahsch-Anhaltische  SprengstofE  A.  <;..  in  their  Ger.  Applica- 
tion 38,595  of  December  2.  1911,  on  the  other  hand  claim  the  addition  of  a 
small  quantity  of  a  silicate,  such  as  kaolin  or  talc,  and  tin-  Kheinische  Dynamit- 
fabrik  adds  both  silica  and  hydrofluoric  acid  or  -odium  -ilico-fluoride.2  The 
addition  of  either  purified  petroleum  or  sodium  fluoride  undoubtedly  accelerates 
the  separation,  and  the  use  of  these  substances  is  extending. 
Conveyance  of  Before  the  invention  of  dynamite  and  blasting  gelatine  nitro-glycerine 
nitro-glycerine  waa  >(,Ilt  \ong  distances  in  the  liquid  state.  The  dangers  involved  led  to 
numerous  accident-,  as  was  inevitable.  In  America  Mowbray  froze  the 
material  for  the  purposes  of  transport,  but  then  it  had  to  be  thawed  again 
before  use,  as  it  is  too  insensitive  in  the  frozen  state.  In  Europe  liquid  nitro- 
glycerine is  now  no  longer  used  as  such,  but  in  America  it  i-  employed  for 
"  blowing  "  oil-wells,  for  which  purpose  it  has  to  be  >ent  by  read,  as  the  railways 
will  not  carry  it.  In  the  works  the  principle  is  adopted  of  mixing  it  with  a 
solid  substance  at  as  early  a  stage  as  possible,  bo  that  the  quantity  of  liquid 
nitro-glycerine  is  reduced  to  a  minimum,  but  until  it  has  been  fully  washed 
and  mixed,  it  must  of  course  be  conveyed  from  one  house  to  another  in  the 
liquid  state.     This  is  sometimes  done  in  closed  trucks  or  trolley-  I    g.  48). 

1  Eastern  Dynamite  Co..  Or.  l'at.   181,489;    C.   L   Reese,  Am.  Pat.  804,817. 

2  Eng.  Pat.  14,586,  of  June  12,  1912  ;    •  ■•  rm.  Pat.  283,330,  of  Od  >ber  10,  1912. 


MANUFACTURE   OF  NITRO-GLYCERINE  227 

In  Germany  the  tendency  is  to  revert  to  trolleys  on  account  of  the  danger 
of  explosions  being  communicated  from  one  house  to  another  by  gutters 
or  pipes.  Where  small  quantities  only  have  to  be  transferred,  as  from  the 
after-separating  and  wash-water-settling  houses  to  the  washing  house,  covered 
buckets  of  indiar-ubber,  gutta-percha,  or  papier  mache  are  used,  and  these 
are  carried  in  the  hand.     In  England  the  bulk  of  the  nitro-glycerine  is,  how- 


Fig.  48.     Truck  for  Conveyance  of  Liquid  Nitro-glycerine,  Repauno,  U.S.A. 
(By  permission  of  E.  J.  du  Pont  de  Nemours  Co.) 

ever,  caused  to  run  from  one  house  to  another  through  open  gutters,  which  Gutters, 
are  usually  made  of  lead.  Pipes  are  not  suitable  on  account  of  the  impossi- 
bility of  inspecting  or  cleaning  them  properly.  All  wash- waters  are  also 
sent  down  open  gutters  to  the  wash- water-settling  house,  as  they  carry  globules 
of  nitro-glycerine.  The  fall  of  the  gutters  should  not  be  less  than  about  1 
in  65  :  they  should  be  free  from  sharp  turns  and  from  all  inequalities  in  which 
nitro-glycerine  can  lodge.  At  the  Royal  Gunpowder  Factory  they  are  joined 
by  butt -welding,  as  this  gives  a  much  smoother  surface  than  lap- welding.  In 
order  to  prevent  the  nitro-glycerine  from  freezing  in  cold  weather,  the  gutter 


22  s 


EXPLOSIVES 


connecting  the  nitrating  house  with  the  washing  house  is  provided  with  an 

outer  jacket  {■((  section  in  Fig.  43),  and  warm  water  is  circulated  in  this  when 
the  outside  temperature  is  low.  The  gutter  is  protected  by  means  of  a  canvas 
covering  fixed  along  one  edge  and  laced  down  on  the  other,  so  that  it  can  easily 
be  turned  hack  for  cleaning  purposes.     After  a  charge  has  been  run  down. 

the  gutter  is  wiped  along  its  whole  Length  with  a  flannel  in  the  direction  of 
the   washing    house   to   remove  any   traces   of   nit  ro-idycerine. 

When  the  riitro-glycerine  has  been  mixed  with  sufficient  gun-cotton  or 

oih.r  absorbent   material  to  render  it    non-liquid   it    is  comparatively   safe. 


Fig.    I1'.     European  Nitro-glycerine  "Hills."     Forcite  Works  al    Baelen-Wezel 
(From  Fah icalion  des  Explosifs,   Brussels,    1909) 


"Mixed  material"  for  the  manufacture  of  cordite  lias  been  transported  in 
very  large  quantities  over  considerable  distances  without  mishap.  When 
the  nitro-glycerine  factory  at  Waltham  Abbey,  near  London,  was  destroyed 
by  an  explosion  on  May  7,  18!)4.  supplies  were  obtained  from  the  Nobel  Factory 
at  Ardeer,  in  Scotland,  in  this  state  until  a  new  factory  was  built,  (bin- 
cotton  in  the  wet  state  was  sent  from  Waltham  Abbey  to  Ardeer,  and  was 
there  diied  and  mixed  with  the  requisite  quantity  of  nitro-glycerine  and 
returned  by  sea,  and  so  the  manufacture  of  cordite  at  Waltham  Abbey  was 
not  brought  to  a  standstill.  Similarly,  when  the  nitrating  house  at  Curtis 's 
and  Earvey's  works  at  Chile,  in  Kent,  was  blown  up  on  February  is,  l(.:i>4, 

gun-col  ton  was  sent   from  there  to  Waltham  Abbey,  and  was  there  converted 

into  mixed  material  and  sent  hack.     Messrs.  Curtis 'e  and  Harvey  were  thus 


MANUFACTURE   OF  NITROGLYCERINE 


229 


enabled  to  carry  out  their  Government  contract  for  cordite,  which  was  urgently 
required  for  the  South  African  War.  The  Diineberg  Factory,  near  Hamburg, 
which  makes  the  nitro-glycerine  smokeless  powder  for  the  Germany  Navy, 
obtains  all  its  mixed  material  from  the  neighbouring  dynamite  works  at 
Krummel,  which  was  the  first  uitro-glycerine  factory  erected  by  Nobel  outside 
Sweden. 

Nitro-gylcerine  factories  are  often  built  on  rising  ground  in  order  to  pro-  Location  o 

•         f&ctorv 

vide  a  fall  from  each  house  to  the  next  without  having  to  make  the  nitrating 


Fig.  50.     American  Nitro-glycerine  Hill.  Haskell,  U.S. 
(From  Apphton's  Magazine) 


house  of  great  height.  With  the  nitrator-separator,  however,  the  difference 
of  level  between  the  top  of  the  nitrator  and  the  bottom  of  the  wash-water 
settling  tank  need  not  be  more  than  10  feet,  which  can  easily  be  provided 
for  on  a  flat  site.  One  great  disadvantage  of  placing  a  nitro-glycerine  factory 
on  the  top  of  a  hill  is  that  it  is  very  likely  to  be  struck  by  lightning,  and  if 
that  occurs  it  does  not  seem  thai  any  system  of  lightning  conductors,  however 
complete,  will  prevent  the  explosion  of  the  nitro-glycerine  and  the  conse- 
quent total  destruction  of  the  building.  There  have  been  numerous  cases 
of  such  catastrophes  in  Germany  and  South  Africa.  In  consequence  of 
this  the  danger   buildings  of    the    Hoppecke  dynamite   factory    have  been 


230 


EXPLOSIVES 


Air  supply. 


Thunder- 
storms. 


Limit  boards. 


built    underground  in  a  hill,  and  Bichel  has  put  forward  similar  proposals.1 

That  part  of  the  works  in  which  are  situated  the  buildings  for  the  manu- 
facture "f  Ditro-glycerine  and  other  specially  dangerous  operations  should 
be  separated  from  the  rest  by  a  fence,  and  no  one  should  be  allowed  within 
the  "  danger  area  "  unless  his  duties  take  him  there. 

Provision  must  be  made  for  the  -tilling  of  the  content- of  the  nitratoi 
and  the  washing  tank-,  etc.  in  case  the  air  compressor  should  fail.  This 
can  he  done  by  haying  a  large  reservoir  for  compressed  air  with  an  automatic 
inlet  valve,  bo  that  the  content-  cannot  .-cape  in  the  direction  of  the  com- 
pressor. A  cylinder  of  highly  compressed  carbon  dioxide  or  nitrogen  can 
al-o  he  used  a-  a  reserve  ;  it  -hould  be  provided  with  a  reducing  valve  ami 
a  manometer,  or  other  appliance,  to  -how  how  much  it  contain-. 

If  a  thunder-storm  pass  over  the  factory  all  work  must  in  drying 

and  mixing  houses,  and  the  men  must  retire  to  the  mess-room  or  other  place 

a  ifety.  In  the  nitrating  house  no  fresh  charge  -hould  he  -tailed  whilst 
there  i-  a  thunder-storm  anywhere  near.  All  men  must  leave  the  building 
except  one  to  look  after  the  separation,  and  one  for  the  oitrator  if  a  charge 
l>e  in  the  process  of  nitration.  If  the  storm  becomes  very  threatening,  I 
al-o  should  leave  after  stopping  the  operations.  Charges  in  the  washing 
tanks  may  he  left  with  the  air  turned  on.  In  Germany  it  is  laid  down  that 
the  electric  light  and  power  wires  are  to  be  disconnected. 

Every  nitro-glycerine  house,  like  all  other  danger  building-,  must   have 

a  board  in  the  entrance  >ho\\iiiLr  the  maximum  number  of  workmen  and  the 

test  quantity  of  explosives  that  may  he  in  it  at  one  time.     In  Germany 

the  following  are  the  greatest  number-  of  men  allowed,  exclusive  of  carriers  : 


Use-lists. 


General 
precautions. 


Nitrating  house 
Separating  housi 
Washing  house 
After-separating  house 
Wash-water  house  . 
Denitrating  ho 


At   the   Royal  Gunpowder  Factory,   Waltham  Abbey.   Use-lists  are  also 

po-ted  up.  showing  the  total  number  of  Loose  articles  that  are  allowed  in 
each  house.  Thi-  i-  a  very  valuable  institution,  a-  there  i-  D.0  doubt  that 
many  accident-  have  been  caused  by  the  dropping  or  falling  of  some  heavy 
implement,  or  by  th<  use  of  some  unsuitable  tool.  It  ha-  been  found  possible 
to  limit  the  number  of  loose  article-  to  those  which  appear  in  the  Table  given 

below.      These   only   are   allowed. 

It  need  scarcely  be  -aid  that,  the  most  scrupulous  cleanliness  and  tidiness 

1  8.S.,   1910,  p.    182;    I  ■■    Industrie,   1912,  p.    139. 


MANUFACTURE   OF  NITROGLYCERINE 


231 


must  be  observed  in  all  nitro-glycerine  houses.     Any  nitro-glycerine  that 
may  be  spilt  should  be  wiped  up  immediately  with  a  flannel. 

The  men  in  the  nitro-glycerine  section  should  have  special  clothes  of  a 
different  colour  from  those  of  other  danger  building  men.  There  must  be 
no  pockets.  The  boots  must  be  changed  on  entering  a  danger  building  ; 
those  worn  inside  must  have  no  nails  or  others  parts  made  of  iron.  Keys  and 
other  implements,  that  have  to  be  brought  near  the  buildings,  are  to  be  made 
of  gun-metal  or  other  soft  material. 

To  destroy  spilt  nitro-glycerine  H.M.  Inspectors  of  Explosives  recom- 
mend the  use  of  a  solution  of  1  lb.  caustic  soda  in  H  lb.  water  to  which  is 
added  a  gallon  of  wood  spirit,  or  failing  that  methylated  spirit.1 

Nitro-glycerine  can  be  exploded  readily  on  iron  or  steel  by  an  iron  imple-  Sensitive™ 
ment,  but  with  some  difficulty  only  with  a  brass  one,  or  on  brass  with  an 
iron  one.  Contrary  to  what  might  have  been  anticipated  it  is  more  difficult 
to  explode  a  thin  film  than  a  layer  of  moderate  thickness,  such  as  that  formed 
by  a  small  drop.  It  is  very  difficult  to  explode  nitro-glycerine  on  sheet  lead 
placed  on  stone  by  iron  or  steel  implements  either  by  a  direct  or  a  glancing 
blow.2 

Use-Lists  at  YYaltham  Abbey. 


Nitrating 
House 

Washing 
House 

Wash -water 
House 

Filtering  and 
Mixing  House 

Bags,  rubber    .... 
Bottles,  gutta-percha 
Buckets,  rubber 

3 

6 

6 

1 
12 

Covers,  bucket,  gutta-percha 
Flannels  ..... 

4 

6 
3 

6 
2 

2 

Gauntlets,  rubber 

1 

— 

— 

— 

Gauntlets,  leather 

— 

— 

— 

2 

Overshoes,  rubber 

4 

3 

2 

— ■ 

Socks        ..... 

— 

— 

— 

2 

Thermometers  .... 

3 

3 

2 

1  A.R.,   1904,  p.  62. 


2  A.R.,   1902,  p.  25;    1903,  p.   25. 


(  HAl'I  KH    XVII 
LOW-FREEZING  NITRO-GLYCERINE 

Freezing  of  nitro-glyeerii.  Bfect  of  additions    :    Super-coolin^ 

Droit ro-gJywrine  :  Dinitro-chlorhydrin  :  Dinitro-aoetin  :  Dinitro-forniin  :  TYtra- 
nitro-diglycerine  :  Dinitro -glycol  :    Xitroisobutyl-glycerine    iiit  i 

Fnesngof      0>e  of  the  greatest  drawbacks  attaching  to  nitro-glycerine  explosive*  is  the 

oitro-giycerire  jjability  of  nitroglycerine  to  go  solid  at  moderately  low  temperatures.     The 

melting-point  of  pure  nitro-glycerine  is  13  3:  C.  or  56'  F..1  but  it  can  often 

be  kept  even  in  large  quantities  for  considerable  periods  at  temperatures  much 

Mow  this  without  solidifying,  for  it  shows  in  a  high  degree  the  phenomenon 

:  super-cooling.     In  the  solid  state  it  is  much  less  sensitive  to  the  detonative 

effect  of  fulminate,  and  this  is  a  great  source  of  danger,  for  frozen  cartridges 

are  liable  to  remain  in  the  bore-hole  partly  or  entirely  unexploded.  and  in  the 

sequent  operations  they  are  very  likely  to  be  fired  by  a  blow  with  disastrous 

results.     Whether  frozen  nitro-glycerine  is  more  sensitive  to  blows  than  when 

liquid  the  evidei.  newhat  contradictory .     ELM.  Inspectors  of  Explosives1 

tried  the  effect  of  a  falling  weight  of  5  lb.  on  little  cylinders  of  dynamite  i  inch 

diameter  and  J  inch  high,  placed  between  gun-metal  discs,  and  found  that 

whereas  the  unfrozen  material  was  sometimes  exploded  with  a  fall  of  3<»  in 

the  frozen  dynamite  was  never  exploded  with  a  single  blow  of  the  weight 

falling  4^  inches,  but  a  feeble  explosion  was  produced  at  the  second  blow. 

Later  on  further  experiments  were  carried   out   with   other  nitroglycerine 

explo>ive>.3     Thin  >lices  of  the  explosive  about  the  size  of  a  shilling  and  about 

.  inch  thick  were  placed  between  brass  plates  1  inch  square  and  1    8  inch 

thick.     The  :-liee  thus  sandwiched  was  placed  on  an  anvil,  and  a  58-Ib.  weight 

I  to  fall  on  the  uj  q  -  plate.     The  critical  or  probable  exploding 

points  under  these  conditions  were  found  to  be  about  a>  follows  : 

Unfrozen  ftpjou 

Blasting  gelatine 

Gelatine  dynamite    . 

Dynar:.  .... 

The  tigures  give  the  number  of  feet  of  fall  of  the  weight  which  caused  expL 

1  Ka-      —  Z2i      Xauckhoff,  8J3.,    1911,    p.  124:   HihU-rt.    m),  InL  Canp 

App.  Chfrn..  vol.  iv.  p.  37.  2  A.K..    18*3  ■  A.R..   1889. 


12' 

r 

to  8' 

g'to 

r 

— 

LOW-FREEZING   NITROGLYCERINE  233 

The  dynamite  was  in  slices  about  the  size  and  thickness  of  a  sixpence.  It 
was  also  found  that  frozen  dynamite  was  very  liable  to  detonate  when  it  was 
ignited  whereas  the  plastic  material  merely  burnt  away  under  the  same 
conditions.  Some  hard  frozen  blasting  gelatine  laid  on  a  sloping  board  and 
fired  at  with  a  rifle  at  20  yards'  range  detonated  powerfully,  whereas  unfrozen 
cartridges  under  similar  conditions  did  not  explode,  and  cartridges  of  the 
explosive  frozen  only  slightly  were  merely  scattered. 

On  the  other  hand,  Will,1  in  falling  weight  and  shooting  experiments, 
found  the  frozen  nitro-glycerine  explosives  less  sensitive  in  all  cases.  The 
differences  in  the  case  of  the  falling  weight  experiments  were  probably  due 
to  the  use  of  very  much  smaller  quantities  of  explosive  by  Will.  It  is  the 
increased  resistance  offered  by  the  frozen  explosives  that  makes  them  more 
dangerous  to  manipulate.  If  a  very  thin  layer  be  used  it  is  the  resistance 
of  the  supporting  surface  that  comes  into  play  and  not  that  of  the  explosive, 
and  when  fired  with  a  detonator  also,  the  hardness  of  the  material  has  but 
little  influence.  But  miners  have  to  do  with  whole  cartridges  of  explosive, 
and  that  these  have  special  dangers  is  shown  by  the  accidents  that  occur  in 
spite  of  the  warnings  that  have  been  issued  repeatedly  and  the  regulations  that 
require  the  use  of  proper  warming-pans.  Thus,  in  the  annual  report  of  H.M. 
Inspectors  of  Explosives  for  1911,  the  following  cases  are  cited  : 

Xo.  2,  Jan.  4.     Man  injured  whilst  ramming  home  a  frozen  charge  of  gelignite. 

Xo.  32,  Jan.  16.  A  man  inserted  an  iron  spike  into  a  cartridge  of  Samsonite 
preparatory  to  attaching  the  detonator.  The  cartridge  was  probably  frozen.  Two 
injured. 

Xo.  35,  Jan.  3.  Man  injured  breaking  a  frozen  cartridge  of  Samsonite  in  two  by 
hand. 

Xo.  60,  Jan.  4.  A  labourer  was  about  to  charge  a  shot-hole  when  he  fell  and  knocked 
the  explosive  against  the  rock.  Apparently  the  gelignite  had  not  been  thawed  suffi- 
ciently or  had  become  hard  again.     Man  injured. 

Xo.  92.  Mar.  22.  A  man  was  in  the  act  of  breaking  a  frozen  gelignite  cartridge  with 
his  hands  when  it  exploded.     Two  injured. 

No.  106,  Mar.  10.  Whilst  a  miner  was  handling  a  congealed  gelignite  cartridge  it 
exploded  and  .injured  him. 

No.  117,  Mar.  25.  A  miner  dropped  a  "hard"'  gelignite  cartridge  on  a  tram-rail 
and  it  exploded.     One  injured. 

No.  119,  Mar.  25.  A  charge  of  undoubtedly  hard  frozen  Samsonite  exploded  whilst 
being  rammed  home  with  a   wooden  rammer.     Two  injured. 

Xo.  158,  Apr.  11.  A  chargeman  was  making  a  hole  for  a  detonator  in  a  Rippite  cart- 
ridge when  it  exploded.  Apparently  the  cartridge  had  been  rather  hard,  and  he  rested 
it  on  the  ground  and  was  pressing  or  knocking  the  pointed  end  of  the  steel  nippers  into 
it.      One  injured. 

Similar  cases  have  occurred  in  other  years,  but  not  always  with  the  same 
1  Zeits.  Berg.,  HiUten-u.  Salinenwesen,   1905. 


234 


EXPLOSIVES 


fortunate  absence  of  fatal  injuries.  C.  Herlin  has  carried  out  experiments 
in  which  the  conditions  of  some  of  these  accidents  were  reproduced  more 
closely.  Il<-  dropped  balls  of  explosive  weighing  40  to  11<>  grammes  from 
various  heights  up  to  12*3  metres  on  to  an  iron  plate.  Frozen  explosives 
went  off  every  time  if  the  quantity  and  the  length  of  drop  were  sufficient, 
but  partly  thawed  balls  never  exploded,  and  presumably  the  unfrozen  material 
did  not   cither.1 

The  following  Table  Bhows  how  certain  classes  of  accident  are  much  more 
frequent  at  those  times  of  the  year  when  nitro-glycerine  is  liable  to  lie  frozen. 
Only  those  accidents  in  which  an  explosive  containing  over  10  per  cent,  of 
nitro-glycerine  was  involved  are  shown  here. 


Jan. 

1 

Feb 

1 
1 

2 

Mar. 

Apr. 

M  i  \ 

1 
1 

2 

39 

June 
2 

2 
29 

July 

1 
1 

2 
31 

Aug. 

1 
2 

1 
3 

Sep. 

1 

( )ct . 

1 
1 

Nov. 

Dec. 

Ramming nr  atomnnning  charge  . 
Boring  into  unexploded  duo  ges 

Striking  unexploded  charges  in 
removing  debris. 

4 
1 

5 
94 

1 
2 

3 

58 

1 

1 

Total  of  above  causes,  1914 

1 

1 

2 

1 

3 

Total  in  pasl  14  years 

75 

ill 

in 

26 

21 

34 

GO 

In  addition  to  these  there  were  up  to  the  end  of  1  i » 1  -4  1  10  accident-  in  thawing 
cartridges  of  frozen  nitro-glycerine  explosive-,  causing  death  to  85  persons 
and  injuries  to  143  others.  It  is  true  thai  all  except  one  of  these  accidents 
would  have  been  avoided,  if  the  explosives  had  been  thawed  in  the  regulation 
manner.  The  one  exception  was  due  to  the  thawing  of  Borne  unstable  explo- 
sive, the  heat  tesl  of  which  had  been  masked  by  the  addition  of  mercuric 
chloride. 

These  special  dangers  and  the  trouble  in  having  to  keep  the  explosives 
in  heated  magazines  during  cold  weather,  or  of  thawing  them  and  keeping 
them  thawed  up  to  the  time  of  using  them,  as  well  as  the  great  difficulty  in 
preventing  the  workmen  thawing  them  in  an  irregular  manner,  has  caused 
endeavours  to  he  made  to  manufacture  nitro-glycerine  explosives  which  will 
not    freeze  so  readily.       For  this  purpose  use  is  made  of  the  facl    thai    when  a 

Bubstance  is  dissolved  in  a  liquid  the  freezing-point  is  depressed  in  accordance 

1  8.S.,   L914,  j..  390. 


LOW-FREEZING  NITROGLYCERINE 


235 


ill 

with  the  equation  A  =  E  •  ,  in  which  A  is  the  depression  of  the  freezing- 
point  produced  by  the  addition  of  m  grammes  of  a  substance  of  molecular 
weight  M  to  100  grammes  of  the  solvent,  and  E  is  a  constant,  which  represents 
the  depression  produced  by  1  gramme-molecule.     It  can  be  calculated  by  the 

RT2 

formula  E=-—_      in  which  R  is   the  gas  constant  (  =  2),  T  the  absolute 
100VV  ° 

temperature  of  the  freezing-point  and  W  the  latent  heat  of  fusion.  As  early 
as  1885  Nobel  patented  the  lowering  of  the  freezing-point  of  nitro-glycerine 
by  dissolving  other  substances  in  it.1 

The  behaviour  of  nitro-glycerine  when  cooled  was  investigated  by  Nauck- 
hoff,2  and  was  found  by  him  to  be  quite  normal.  He  determined  the  latent 
heat  of  fusion  as  23-1  cal.  per  gramme,3  and  hence  E  =  70-5.  The  following 
Table  gives  some  of  the  depressions  of  the  freezing-point  observed  and  calcu- 
lated by  Nauckhoff  : 


Depression 

of  Freezing 

Substance  Dissolved 

Molecular 
Weight. 

Grammes 
per  100  g. 

N/G 

po 

nt 

Observed 

Calculated 

Nitro-benzene     .... 

123 

0-637 

0-30° 

0-37° 

.... 

99 

1-334 

0-73° 

0-76° 

Dinitro  -benzene . 

168 

0-644 

0-23° 

0-27° 

„ 

1-508 

0-59° 

0-63° 

Trinitro -benzene 

213 

1-935 

0-56° 

0-64° 

Dinitro -toluene  .... 

182 

1057 

0-37° 

0-41° 

Dinitro -naphthalene    . 

218 

0-707 

0-23° 

0-24° 

Nauckhoff  also  determined  the  freezing-,  or  rather  melting-points  of  a 
number  of  mixed  explosives  : 


Nitro-glycerine   .           .           .           .           100 
Nitro-benzene     .           .           .           .             19-7 
Nitro -cellulose     .           .           .                       10 

Freezing-point    .           .           .           .               1-0° 

100 
10 

8 

5-0° 

100 
5-9 
51 

7-5° 

100 
5-7 
70 

9-0° 

1  French  Pat.   170,290  of  July  24,   1885.  -  Aug.,   1905,  pp.   11,  35. 

3  H.  Hibbert  and  G.  P.  Fuller  found  the   latent    beat  to  be  33-2  cal.  per  gramme   or 
7-54  cal.  per  mol.  (J.  Am.  Ghem.  Soc.,   1913,  p.  978). 


l':;<; 


EXPLOSIVES 


Nitro-glycerine 

50 

50 

50 

:,.! 

50 

50 

50 

50 

50 

50 

;»:5 

Nitro-cellulose 

."> 

."> 

4 

•"> 

5 

5 

5 

■"> 

5 

5 

5 

Ammonium  Nitrate 

4<» 

35 

4<» 

35 

40 

34 

40 

40 

40 

40 

42 

Nitro-benzene 

."> 

L0 

-  - 

— 

— 

— 

— 

— 

— 





Dinitro-benzei 

— 

— 

5 

10 

— 

— 

— 





. . 

o-Nitro-toluene 

— 







5 

11 









p-Nitro-tolueno 

— 









5 









Nitro-naphthalene 

— 

— 

— 

— 

— 



5 







o-Nitro-phenol 

5 

Aniline 

— 

— 

— 

5 

— 

Fn  ezing-point 

5 

g 

4 

6° 

If 

6 

~l: 

4= 

in 

The  freezing-point  of  the  nitro-glycerine  used  for  these  experiments  was  about 
ro-5  .  Taking  into  account  this  fact,  and  that  the  law  of  the  depression  of 
tin-  freezing-point  is  strictly  true  only  for  dilute  solutions,  the  figures  found 
agree  fairly  well  with  those  calculated.  The  low  freezing-point  of  the  original 
nitro-glycerine  was  due  of  course  to  the  presence  of  some  impurity  in  the 
nitro-glycerine,  probably  dinitro-glycerine,  of  which  about  8  per  cent,  would 
be  required  to  produce  this  depression.  Nauckhofi  considers  that  10-5  is 
the  normal  freezing-point  of  commercial  nitro-glycerine.  but  thi>  no  doubt 
depends  upon  the  composition  of  the  acid  used  and  the  proportion  of  acid 
to  glycerine.  There  is  no  doubt  that  much  of  the  nitro-glycerine  manufactured 
La  almost   pure  trinitrate  and  freezes  near  )3°. 

The   melting-points  of   nitro-glycerine,   dinitro-chlorhydrin  and  mixtures 
of  them   were  determined   bv   Kast  :  ' 


Nitro-glycerine 

Din 

tro-chlorhydrin 

Melting-point 

Observed                            Calculal 

J  4 

g- 
0 

13-4° 

21 

21 

90° 

9-6 

21 
21 

4-2 

0-3 

6-2    -7-0° 
40° 

6-1 

20 

0 

30-8 

6-6°-6-8° 

— 

Kasl  also  gives  the  "  free/ing-|i<>int s,"  hut  as  the  liquids  were  cooled  con- 
siderably below  the  true  freezing-points  before  being  inoculated  with  a 
crystal,  the  composition  had  been  altered  by  the  separation  of  crystalline  nitro- 
glycerine before  the  temperature  rose  to  a  maximum,  and  this  consequently 

1  >.>..   1906,  p.  225. 


L(  )\V-FREEZING   NITRO-GLYt  IERINE 


237 


did  not  correspond  with  the  true  freezing-point,  which  is.  of  course,  identical 
with  the  melting-point.  Kast  observed  that  nitro-glycerine  can  also  crystal- 
lize in  another  or  "labile"  form,  the  melting-point  of  which  is  more  than 
11°  below  that  of  the  stable  form.  Freezing-point  determinations  were  also 
carried  out  with  mixtures  inoculated  with  crystals  of  this  form  : 


Nitro-glya  rine 

1  tinitro-chlorhydrin 

Melting-p  »int 

( observed 

(  alculated 

24 
12 
18-4 
21-6 
0 

0 
11-5 

5-4 

2-6 

231 

2-7:  to         2-9 

about  —12° 

—7°  to  —  5° 

—0-8°.  to  —  0-6° 

5-1°  to         5-2° 

—31 -.5 
—81 
—20 

cooling. 


A  different  sample  of  dinitro-chlorhydrin  was  used  for  this  series. 

Nitro-glycerine  preparations  do  not  necessarily  go  solid  when  the  tempera-  Super- 
fine is  reduced  below  the  freezing-point,  on  the  contrary  they  can  often  be 
kept  for  months  at  a  temperature  considerably  lower  without  solidifying. 
This  property  of  super-cooling  is  intimately  connected  with  a  slow  rate  of 
crystallizing,  when  solidification  does  start,  and  this  again  appears  to  be 
related  to  high  viscosity.  The  rate  of  crystallization  of  a  given  substance 
depends  also  upon  the  temperature  ;  as  this  is  reduced  below  the  freezing- 
point  the  rate  increases  at  first,  reaches  a  maximum  and  then  falls  again. 
Xauckhoff  gives  the  following  Table  :  1 


Rate  of  crystallization 
mm.  per  min. 

Substance 

Temperature 

Super-cooling 

Glvcerine    .... 

0° 

10° 

0011 

Kitro-glvcerine    . 

5° 

7-3° 

0145 

„                    ... 

0° 

12-3° 

0-183 

... 

—4-9° 

L7-2 

0-2(37 

,,                   ... 

—  17° 

29-3° 

0-125 

Betol           .... 

— 

— 

1           maximum 

Guaiacol     .... 

— 

— 

6 

Azo -benzene 

— 

— 

;.:<» 

Phosphorus 

■ — - 

60.000 

The    rate    of    crystallization    is    further    reduced,    if    the    nitro-glycerine    is 

1  Ang.,  1905,  p.   16. 


238  EXPLOSIVES 

gelatinized  with  collodion,  but  if  it  is  absorbed  in  kieselguhr  its  tendency  to 
crystallize  is  increased.  When  a  cartridge  of  a  nitro-glycerine  explosive  has 
once  been  fro7.cn,  it  has  a  much  greater  tendency  to  become  hard  again  as 
soon  as  the  temperature  falls  below  the  freezing-point.  This  is  probably  due 
to  tli«'  separation  of  globules  of  practically  pure  nitro-glycerine.  which  only 
mix  again   with   the   impurities  and   other  constituents  very  slowly. 

The  first  attempts  to  reduce  the  freezing-point  of  nitro-glycerine  were 
with  nitro-beu/.etie  '  and  nit  ro-1  oluene.-  Unfortunately  they  not  only  reduce 
the  sensitiveness  of  the  explosive,  a  difficulty  that  can  be  overcome  by  the 
use  of  a  stronger  detonator,  but  also  diminish  the  power  and  the  velocity  of 
detonation.  For  blasting  hard  rock  these  drawbacks  are  of  the  greatest 
importance,  but  for  safety  explosives  for  use  in  coal-mines,  etc.,  far  Jess  so  ; 
in  fact  it  is  necessary  to  reduce  the  power  and  the  velocity  of  detonation  in 
order  to  make  the  explosive  safe,  and  for  blasting  soft  lock  too  high  a  rate 
of  detonation  is  undesirable.  Hence  various  nitro-hydrocarbons  are  used 
as  constituents  of  many  safety  explosives.  In  order  to  reduce  the  freezing- 
point  to  any  great  extent  it  is  necessary  that  the  proportion  of  dissolved 
substance  to  nitro-glycerine  should  be  fairly  high,  and  the  greater  the  mole- 
cular weight  of  the  addition,  the  larger  must  be  its  proportion.  But  sub- 
stances  of  very  low  molecular  weight  cannot  be  used  because  they  are  volatile. 
Therefore,  in  order  not  to  reduce  the  efficiency  of  the  explosive  too  much,  it 
is  desirable  to  add  some  substance  that  is  almost  as  effective  an  explosive  as 
nitro-glycerine.  There  are  a,  number  of  substances  closely  allied  to  trinitro- 
glycerine,   which  can  be  used. 

Methods  for  the  manufacture  of  dinitro-glycerine  have  been  devised  by 
Mikolajczak  :i  and  the  Zentralstelle  ,4  Will  has  pointed  out  that  dinitro- 
glycerine  is  liable  to  go  solid  at  quite  moderate  temperatures,  and  that  it 
baa  the  further  disadvantage  that  it  combines  with  water  of  crystallization, 
is  soluble  in  water  and  acids  and  somewhat  hygroscopic.  To  what  extent 
these  troublesome  qualities  disappear  when  it  is  mixed  with  several  times 
its  weight  of  trinitro-glycerine  there  is  no  published  evidence  to  show,  but 
the  results  of  experience  with  this  substance  in  Prance  do  not  appear  to  have 
been  very  favourable.5 

Dinitro-chlorhydrin  is  easier  and  cheaper  to  prepare  and  purify,  and  is 
now  used  to  a  considerable  extent  for  reducing  the  freezing-point  of 
explosives,  [t  mixes  with  trinitro-glycerine  in  all  proportions  and  gelatinizes 
collodion  cotton  equally  well.     As  regards  power,  Roewer  found  that  there 

1  Rudberg,  Swed.  Pat.,  April  :!<>.   L866. 

2  Volney,  Am.  Pat.,  March  •">,  1872;    Wahlenberg  and  Smulstrom,  Swed.  Pat.  1877. 

3  Am.  Pats.  789,436  of  September  II.  I 'toe.  reissue  12,669  of  July  2,  1907,  and  830,  909 
of  January    26,    1909.  '   <  ler.  Pats.   181,385  and   175,751. 

6  See  Vennin,  Poudres  et  Exphsijs,  p.   367. 


LOW-FREEZING   NITROGLYCERINE  239 

was  tittle  difference  between  explosives  made  with  nitroglycerine  alone  and 
those  made  with  a  mixture  in  which  20  per  cent,  of  the  nitro-glycerine  had 
been  replaced  by  dinitro-chlorhydrin.  In  the  following  Table  the  columns 
marked  A  are  those  obtained  witli  the  nitro-glycerine  explosives,  and  B  those 
with  the  mixtures  of  nitro-glycerine  and  dinitro-chlorhydrin  : 


Guhr  dynamite 

Blasting  gelatine 

Gelignite 

A 

B 

A 

B 

A 

B 

Trauzl  Test,   c.c.      . 
Ballistic  Pendulum, 

kg.m. 

300 
740 

301 
75-9 

555 
111-4 

541 
111-4 

395 

90-8 

381 
88-5 

The  calorimetric  figures  calculated  for  65  per  cent,  gelatine  dynamite 
(63  per  cent,  nitro-glycerine  or  mixture,  2  per  cent,  collodion  cotton.  26  per 
cent,  sodium  nitrate,  and  9  per  cent,  cellulose)  also  give  similar  results  : 


A 

B 

Heat  evolved  per  kg. 

.      1.244  Cal. 

1,278  Cal. 

Temperature  of  Explosion 

.      2,939° 

2,835° 

Gas  produced  per  kg. 

.      7,168  litres 

6,872  litres 

Dinitro-chlorhydrin  is  a  constituent  of  the  following  explosives  authorized  Dinitro- 
for  transport  by  rail  in  Germany  :    Gelatin  Astralit,  Gelatin  Wetterastralit,  chlorhydrir 
Gelatin  Donarit,  Gelatin  Westfalit,  and  Perilit. 

In  order  to  make  a  mixture  of  nitro-glycerine  and  nitro-chlorhydrin,  the 
chlorhydrin  can  be  mixed  with  the  glycerine,  and  the  mixture  nitrated  and 
washed  in  the  usual  way. 

Dinitro-chlorhydrin  is  practically  insoluble  in  acids  and  water,  and  is  not 
hygroscopic,  but  has  the  disadvantage  that  on  explosion  it  gives  off  hydro- 
chloric acid,  which  makes  it  unsuitable  for  use  underground,  unless  sufficient 
of  an  alkali  nitrate  or  other  compound  be  added  to  convert  all  the  chlorine 
into  an  inorganic  chloride.     This  difficulty  does  not  occur  if  the  third  oxygen 
atom  in  the  glycerine  molecule  be  combined  with  the  radicle  of  an  organic 
acid  instead  of  chlorine.     Vender  has  found  that  the  acetyl  and  formyl  deriva- 
tives, mono-acetin  and  mono-formin,  can  be  nitrated  and  give  a  good  yield, 
provided  that  the  mixed  acid  contains  more  nitric  than    sulphuric  acid.1 
Dinitro-acetin,    C3H5(N03)2.(C2H302),     he    says,    can    be    obtained    with    a  Dinitro- 
yield  of  95  per  cent,  by  nitrating  40  parts  of  acetin  with  a  mixture  of  100  acetin* 
parts  nitric  acid  and  25  of  25  per  cent,  oleum.     Dinitro-formin  may  be  made  Dinitro- 
by  heating  100  kg.  glycerine  with  50  kg.  oxalic  acid  first  at  100°  and  then  formin- 

1  Ger.  Pats.  209,943  of  April  27,  1906,  and  S.S.,  1907,  p.  21. 


240 


EXPLOSIVES 


Nitro-iso 
butyl- 
glyctrine 
nitrate. 


at  14"     to  150°,  and  then  nitrating.     The  product  has  a  specific  gravity  of 
1  -57,  contain-   1 ."»  7  j>er  cent.  X  and  con>i>T-  j>er  cent,  dinitro-formin 

and  67  per  cent,  nitro-glycerine.     It  is  unfreezable  and  gelatini/  lion 

-  if  not  better  than,  nitro-glycerine. 
Bv  treating  it  in  various  wa\  -  _  rine  can  be  condensed  to  di-glycerine : 
i(  H.<»  H."  -  I  HjiH .(  HOB  (  B .  .<>.  and  this  on  nitration  yields 
a  tetra-nitrate  ('4H1(>X«0,3.  which  reduces  the  freezing-point  of  nitro-glycerine 
just  as  the  other  substances  that  have  been  mentioned.  The  formation  "f 
di-glycerine  b  -  lied  in  the  Z>  t  tralttdk.1  and  it  was  found  that  the  con- 
version "  effected  by  heat  alone.  By  heating  glycerine  for  seven  or 
eight  hour-  -  295°8om<  60  per  cent,  of  di-glycerine  is  formed  together 
with  4  to  »>  ]>cr  cent,  of  poly -glycerines.  The  constituents  can  be  separated  by 
distillation  at  a         -  of  8  t<>  1"  mm.     According    to    Eng.  Pat.  24 

24,  1910,  taken  out  by  Nobel's    Explosives  Co.,  W.  Rintoul  and 
A.  6.   Innes,  the  conversion  i-  best  effected  by  heating  at   a  temperature  of 
in  a  current  of  inactive  gas.  such  as  carbon  dioxide,  which  carries 
away  the  water  formed,  and  keeps  the  liquid  in  a  state  of  agitation. 

Claessen.  in  Eng.  Pat.  9572  of  1908,  claims  the  use  of  a  small  proportion 
kali  :    by  heating  t      _~"  _  -        nth  0-5  per  cent,  the  conversion  i> 

effected  in  a  comparatively  short  time. 

Pure  di-glycerine  boils  at  24  _  aider  a  of  8  mm.  :    it  is 

a  colour!  -  -  eet  liquid  readily  soluble  in  water  ;  it>  specific  gravity  i> 
and  it  is  eleven  times  more  -  -  than  glycerine.  Tetra-nitro-di-glycerine 
-imilar  to  nitro-glycerine.  A  mixture  of  glycerine  with  about  2.".  per 
cent,  di-glycerine  can  be  nitrated  in  the  >ame  way  as  glycerine  alone,  and 
the  product  is  unfreezable.  Guhr  dynamite  made  with  such  a  nitro-glycerine 
produced  as  great  an  effect  in  the  lead  block  as  ordinary  dynamite. 

Dinitro-glyc"!  (  H  X<  '   '  H  X'  I    is  used  by  t;      S      ■  te  anonyme  dlSxplo- 

et  de  Produits  chimiques.*     It>   power  according  to  calculation  is  4  per 

cent,   greater  than  that   of  nitro-glycerine.     In   the  calorimetric  bomb  the 

Its  obtained  indicated  a  superiority  of  8  to  2o  per  cent,  according  to  the 

method  of  interpreting  the  results  :    by  the  lead  block  te>t  the  results 

about  equal.     The  S  -rate  that  at  the  present  high  price  of  glycerine 

nitro-glyco]  can  be  made  at  a  cost  not  much  greater  than  that    of    nitr<>- 

erine.     It  is  more  volatile  than  nitro-glycerine  :    its  specific  gravity  is 

at    15  . 

If  nit ro- methane  be  mixed  with  4  part-  of  4«i  per  cent,  formaldehyde,  and 

a  little  potassium   carbonate  or  bicarbonate  be  added,   condensation  takes 

place  with  the  formation  of  nitro-isobutyl-glycerine  :    V  I .'  B         SB  (  (  »H  = 

V  I  _'     I  H  '  >H      a  crystaDini  .nee  rea<lily  soluble  in  water  and  alcohol 


3JS.,   1906,  p.  231. 


2  P.  1911-1%  p. 


LOW    FREEZING    NITRO-GLYCERINE  241 

but  less  soluble  in  ether.  It  melts  at  158°  to  1590.1  If  this  be  purified 
by  recrystallization  and  then  nitrated  with  mixed  acid,  the  trinitrate 
N02C(CH2N03)3  is  formed,2  a  liquid  of  specific  gravity  1-68  and  very  low 
freezing-point.  At  present  it  is  not  of  practical  importance  on  account  of 
the  high  price  of  nitro-methane,  but  if  an  inexpensive  method  of  making  this 
could  be  devised,  it  could  be  used  commercially. 

1  Henry,  Compt.   Rend.,   1899,  I.,  p.   1154. 

2  F.  E.  Matthews,  Brit.  Pat.  6447  of  1914  ;  Hofwhnmer,  S.S.,  1912,  p. 


VOfc    ,.  Jfi 


PART  VI 

NITRO- AROMATIC 
COMPOUNDS 


CHAPTER   XVIII 
BY-PRODUCTS    OF    COAL    DISTILLATION 

Aromatic    compounds  :  Distillation    of    coal  :  Coal-tar  :  Nomenclature  :  Benzol 
from  gas  :  Distillation  of   coal  tar  :  Toluene  from  petroleum  :  Carbolic  Acid  : 
Phenol  from  benzene  :  Naphthalene  :  Yields 

Very  great  and  increasing  use  is  made  of  the  nitre-derivatives  of  aromatic  Aromatic 
substances   as  explosives   and  in  the  preparation   of  composite   explosives.  comP°unds 
The  principal,  but  not  exclusive,  source  of   the  aromatic  compounds  is  the 
destructive  distillation  of  coal. 

When  complex  organic  materials  are  submitted  to  destructive  distillation  Distiiiatior 
they  yield  as  a  rule  three  classes  of  products  :  solid,  liquid  and  gaseous.  Of  of  coal- 
the  products  from  coal  the  gas  and  solid  (coke)  are  used  as  fuel.  The  liquid 
products  are  ammoniacal  liquor  and  tar,  obtained  on  cooling  the  gas  and 
scrubbing  it.  Until  recently  ammoniacal  liquor  was  almost  the  only  source 
of  ammonia,  but  it  is  now  meeting  severe  competition  from  synthetic  ammonia, 
for  which  see  Chapter  VIII. 

The  quantity  and  composition  of  the  tar  naturally  depends  upon  the  Coal-tar. 
sort  of  coal  carbonized  and  the  temperature  and  type  of  the  retorts.  The 
higher  the  temperature  the  greater  is  the  yield  of  gas,  but  if  the  temperature 
be  very  high  the  yield  of  tar  is  less,  and  there  is  in  it  a  smaller  proportion  of 
the  simpler  aromatic  compounds,  such  as  benzene,  toluene  and  phenol.  In 
the  large  gasworks  there  has  been  a  tendency  to  carbonize  at  higher  tempera- 
tures than  was  formerly  the  practice,  and  consequently  the  tars  produced 
have  not  been  of  as  great  value  as  those  from  small  country  gasworks.  The 
modern  continuous  vertical  retort,  however,  yields  a  considerable  quantity 
of  good  tar.  The  quantity  of  tar  varies  from  about  4  to  10  per  cent,  of  the  coal 
and  averages  about  5  per  cent.  ;  it  contains  generally  less  than  1  per  cent, 
each  of  benzene  and  toluene.  The  composition  of  coke-oven  tar  is  similar, 
but  varies  between  wide  limits. 

Coal  tar  is  a  thick  black  liquid  of  specific  gravity  11  to  1-3.  It  is  a  very 
complex  mixture  from  which  various  valuable  constituents  can  be  separated 
by  fractional  distillation  combined  with  treatment  with  chemicals.  Owing 
to  the  complexity  of  the  mixture  only  those  substances  are,  as  a  rule,  separated 
in  a  state  of  comparative  purity  <  n  the  commercial  scale  which  are  present 
in  the  largest  proportions,  or  which  possess  some  physical  or  chemical  pro- 
perty which  facilitates  their  isolation.      Of  these  substances  the  most  important 

245 


246 


EXPLOSIVES 


are  the  aromatic  hydrocarbons,  benzene,  toluene,  naphthalene  and  anthracene, 
and  the  aromatic  alcohols,  phenol  or  carbolic  acid,  and  cresol  or  cresylic  acid. 
All  these  art-  used  in  the  manufacture  of  synthetic  dye-stuffs,  drugs,  etc., 
and  toluene,  benzene,  phenol  and  naphthalene  are  also  used  in  the  manufacture 
of  nitro-exploeives,  especially  toluene  and  phenol.  Hence  the  demand  for 
these  substances  i-  sometimes  difficult  to  meet,  especially  in  the  case  of  toluene. 
Benzene  and  naphthalene  on  the  contrary  are  obtained  in  abundant 
quantities.  The  following  are  the  melting- and  boiling-points  of  the  principal 
substances  in  coal  tar  : 


3 

Formula 

Molecular 

Mell     b 
P  tint 

Boiling- 
point 

Benzene 

C'6H6 

78 

56 

3    .    C 

Toluene 

CTH9 

92 

—92 

lln  7 

Phenol 

•         l'cH:OH 

'.•4 

43 

182 

Ortho-creao] 

C7HTOH 

108 

30 

188 

Rfeta 

. 

.. 

4 

200-5 

Pal., 

. 

.. 

36 

2011 

hthalaoe 

C'10H8 

128 

80- 1 

218 

Ant  lira  eene. 

(    HH10 

17S 

211 

351 

Nomenclature.  The  aromatic  hydrocarbon,  < '6H ,,  was  formerly  called  benzol  or  benzole,  but 
in  scientific  English  its  name  is  now  benzene,  the  termination  -ol  being  restricted 
to  1  iodic-,  of  the  nature  of  an  alcohol  and  containing  a  hydroxyl  group  I  OH).  The 
name  benzol  is  applied  commercially  to  volatile  distillates  obtained  by  the  de- 
structive distillation  of  coal  and  rectified  so  as  to  boil  between  aMoiit  80l  and  130°. 
The  next  hydrocarbon  of  thi>  series,  I  '6H5.('H2.  has  similarly  had  its  name  altered 
from  toluol  to  toluene.  Different  grades  of  benzol  are  distinguished  by  the  per- 
centage which  distils  over  below  100  C.  from  a  plain  still  or  retorl  without  a 
dephlegmating  column,  thus  90  per  cent,  benzol  is  a  liquid  of  which  90  per  cent, 
distils  over  below  the  boiling-point  of  water.  According  to  Knu  mer  and  Spilker1 
the  following  are  the  mean  compositions  of  the  benzols  used  in  colour  works  : 


90  per  cent.             50  j>  i  cent. 
Benzol                      Benzol 

3  '  per  cent. 
Benzol 

Benzene   ..... 
Toluene    ..... 
Xylene      ..... 
Impure                  .... 

1.V4 

149                         M  :: 
2-2                          12  4 
2-0                            1-9 

L3-5 
73-4 

11-7 
1-4 

Mii-pratt.  //'//('//--/'-A  (hi-  technisehen  Chemie,  4th  ed.,  8,  pp.  '■>'■>  <t  teq. 


BY-PRODUCTS   OF  COAL  DISTILLATION 


247 


Benzine  is  a  volatile  distillate  from  petroleum  having  about  the  same  range 
of  boiling-points  as  benzol.  It  consists  mostly  of  hydrocarbons  of  the  paraffin 
and  olefine  series.  In  German  benzene  is  still  called  benzol  ;  in  French  it 
is  sometimes  called  benzine. 

The  alcohol  corresponding  to  benzene  is  phenol,  C6H5OH.  Unlike  ordinary 
alcohol  it  has  decided  acid  properties  and  is  often  called  carbolic  acid,  but 
this  term,  like  "  benzol,"  is  more  generally  applied  to  commercial  products 
containing  other  similar  substances  and  impurities  as  well  as  phenol. 

The  quantities  of  benzene  and  toluene  contained  in  the  tar  are,  however,  Benzol  fro 
small  compared  with  what  is  carried  away  in  the  state  of  vapour  in  the  gas.  gas- 
Thus  Bunte  found  that  at  the  Karlsruhe  Gas  Works  the  products  from  the 
distillation  of  100  kg.  of  coal  contained  : 


Primary  Products 

Containing 

Quantity 

Benzene 

Toluene 

40  g. 
312  g. 

Tar 

Gas 

5  kg. 

17  kg. 

(=30  cub.  m.) 

45  g. 
938  g. 

Very  large  quantities  are  now  recovered  from  coke-oven  gas,  especially  in 
Germany,  by  scrubbing  it  with  creosote  or  anthracene  oil.  The  removal  of 
the  benzene  and  toluene  from  coal  gas  destroys  its  illuminating  power  when 
burnt  in  a  fish-tail  burner,  and  reduces  its  calorific  power.  If  these  hydro- 
carbons be  removed  from  gas  for  town  supplies  it  is  necessary  to  reintroduce 
the  greater  part  of  the  benzene.  By  using  a  minimum  of  washing  oil  it  is, 
however,  possible  to  remove  a  considerable  amount  of  the  toluene  with  very 
little  benzene  without  seriously  interfering  with  the  quality  of  the  gas.  The 
volatile  products  are  distilled  off  from  the  washing  oil  by  means  of  live  steam 
or  by  heat  alone.  The  distillate  is  separated  from  the  accompanying  water 
and  fractionated. 

The  tar  x  is  first  freed  as  far  as  possible  from  ammoniacal  liquor,  and  is  Distillation 

of  cOcil  tur, 

then  fractionally  distilled  from  an  iron  boiler  fired  directly,  the  products  being 
separated  either  into  four  or  five  fractions.     The  following  are  the  fractions  : 


I  Crude  naphtha 

11  Light  oil 

III  Carbolic  oil    . 

IV  Heavy  or  creosote  oil 
V  Anthracene  oil 


up  to    110 
110-210 
210-240 
240-270 
above  2"o 


1  Tins  account  of  coal  tar  distillation  is  taken  mainly  from  The  Manufacture  of  Organic 
Dye-stuffs,  by  A.  Wahl,  translated  by  F.  \V.  Attack  (Bell  &  Sons,  1914). 


248  EXPLOSIVES 

or 

I  light  oil up  to  150°  density  less  than    1 

II  Medium  oil. 160-210  ..      mora  „      1 

III  Heavy  oil 210-280 

IV  Anthracene  oil      ....  above  300 

The  residue  remaining  in  the  still  is  pitch,  a  thick  black  mass  which  seta 
practically  to  a  solid.  The  naphtha  is  separated  from  the  water,  which  ]  aaaea 
over  with  it.  and  is  agitated  first  with  dilute  sulphuric  acid  to  remove  basic 
substances,  and  then  with  concentrated  sulphuric  acid  to  resinify  the  unsatu- 
rated hydrocarbons  and  absorb  the  sulphur  compounds,  such  as  thiophen. 
After  washing  twice  with  caustic  soda  and  then  with  water  the  liquid  is  again 
fractionally  distilled,  preferably  through  a  good  dephlegmating  column  similar 
to  that  shown  in  Fig.  69  (p.  344).  giving  benzols  and  solvent  naphtha.  On 
redistilling  these  give  more  or  less  pure  hydrocarbons  :  benzene,  toluene, 
xylenes,  etc..  which  generally  have  still  to  be  further  purified. 

The  light  oil  is  distilled  and  separated  into  two  portions  :  the  fraction 
up  to  170°  is  added  to  the  naphtha  and  the  other  is  added  to  the  carbolic 
oil.  which  is  worked  up  for  phenols  and  naphthalene. 

The  heavy  oils  are  used  for  impregnating  wood. burning  for  heating  purp<  ises, 
for  lighting  and  for  the  production  of  lamp-black,  etc.  They  are  also  heated 
("  cracked  ")  for  the  production  of  illuminating  gas  and  of  more  valuable 
hydrocarbons.  On  leaving  to  crystallize  anthracene  oil  gives  crude  anthra- 
cene, and  on  redistilling  the  oil  gives  a  further  yield  of  anthracene.  This  i- 
purified  by  pressing  washing  with  creosote  oil,  subliming  and  recrystallizing. 
It   i-  used  for  the  manufacture  of  numerous  dye -stuffs. 

According  to  Lunge  the  distillation  of  a  ton  of  coal  tar  yield-  on  an  average  : 

Ammoniaca!  liquor  ....  30  gallons 

Naphtha  .....  (i-3  gallons 

Light   oils  .....  13-4  to    15-0   gallons 

Heavy  oils        .  .  .  .  .  tiS  gallons 

Pitch 0-54  ton 

The  treatment  of  the  tar  is  outlined  in  the  diagram  on  the  next  page. 
Toluene  from  Aromatic  hydrocarbons  are  present  in  petroleums  obtained  in  various 
parts  of  the  world,  but  the  published  information  about  this  is  somewhat 
contradictory.  It  has  been  demonstrated  by  W.  F.  Rittman  and  T.  J. 
Twomey  of  the  U.S.  Bureau  of  Mines  that  if  petroleum  be  heated  under 
pressure  to  temperatures  of  660  C.  and  upwards  considerable  quantities  ol 
aromatic  hydrocarbons  are  formed.  Toluene  and  xylene  arc  apparently 
produced  most  easily.  Benzene  requires  more  strenuous  cracking,  and  its 
formation  reaches  a  maximum  at  a  point  where  toluene  and  xylene  have 
already  fallen  off  considerably.     Naphthalene  begins  to  form  at  about   the 


N 


{      3 


U^ 


250  EXPLOSIVES 

point  where  the  toluene  and  xylene  contenl  is  at  a  maximum,  indicating  that 
it  is  probably  formed  by  tin-  condensation  of  two  molecules  ol  a  monocyclic 
hydrocarbon.  Anthracene  is  formed  under  similar  conditions  to  naphthalene, 
but  requires  even  more  severe  heating.  The  production  of  toluene  was  in 
some  cases  4  per  cent,  of  the  original  pel roleum  and  1 8  per  cent,  of  the  cracked 
oil.  Under  manufacturing  conditions  it  would  perhaps  be  possible  to  obtain 
considerably  better  yield-.1    This  process  i-  being  developed  commercially. 

\V.  A.  Hall  heats  petroleum  products  to  aboul  600  < '.  in  order  to  obtain 
motor  spirit,  ft  lias  been  found  that  the  product  sometimes  contain-  as 
much  as  1<»  per  cent,  of  toluene  and  8  per  cent,  of  benzene.2 

The  fraction  collected  a-  carbolic  oil  consists  mainly  of  naphthalene  and 
phenolic  substances.  The  oil  is  run  into  tanks  and  allowed  to  cool  down, 
whereupon  25  to  30  per  cent,  of  naphthalene  crystallizes  out.  The  oil  sepa- 
rated from  this  has  a  specific  gravity  of  about  1-0025  and  contain-  2.">  to  30 
per  cent,  of  phenols.  It  is  first  concentrated  by  redistilling  it.  preferably 
through  a  dephlegmating  column.  First  some  crude  benzol  comes  over,  then 
a  mixture  of  benzol  and  water.  "When  the  distillate  do  Longer  separates  into 
two  layers  the  receiver  is  changed,  and  it  is  collected  as  crude  carbolic  acid. 
A  further  fraction  may  also  be  collected  consisting  largely  of  cresols  and 
naphthalene.  The  residue  according  to  its  quality  is  either  run  into  the 
creosote  oil  tank  or  used  for  softening  pitch. 

The  rectified  carbolic  oil  i-  next  treated  with  weak  caustic  soda  to  separate 
the  acid  from  the  neutral  hydrocarbons.  For  this  purpose  a  lye  is  used  with 
specific  gravity  not  greater  than  1-075  to  1-10,  as  a  stronger  liquor  would  dis- 
solve some  of  the  naphthalene.  If  pure  phenol  be  aimed  at  fractional  extrac- 
tion with  caustic  soda  is  generally  adopted:  a  quantity  of  the  carbolic  oil 
is  mixed  thoroughly  with  a  quantity  of  caustic  solution  more  than  sufficient 
to  extract  all  the  phenol  so  that  it  also  takes  up  a  small  proportion  of  the 
cresol.  The  aqueous  solution  is  then  drawn  off  and  mixed  with  a  further 
quantity  of  the  carbolic  oil.  when  an  interchange  takes  place,  the  sodium 
cresylate  being  converted  into  sodium  carbolate.  This  method  is  rendered 
possible  by  the  fact  that  phenol  has  a  considerably  greater  affinity  for  the  soda 
than  the  cresols  and  other  homologues  ;  in  other  word-,  it  i-  a  stronger  acid. 

The  solution  of  phenate  or  carbolate  of  soda  i-  purified  by  boiling  and 
blowing  in  steam,  which  removes  any  napht  halene  and  various  other  impurities. 
It  i-  filtered  if  necessary  and  then  treated  with  acid  to  release  the  phenol. 
For  this  purpose  carbonic  acid  i-  now  generally  u^c<\.  but  a  little  Bulphuric 
acid  is  added  to  complete  the  process.  The  solution  of  -odium  carbonate 
thus  obtained  is  reconverted  into  one  of  caustic  soda  by  treating  it  with  lime. 

1  J.  Ind.  Eng.  Chem.,  1916,  p.  i'<».  For  description  of  planl  see  Rittman,  Dutton 
and  Dean,  ibid.,  1916,  p.  351.  Sa  also  <i.  Egloff  and  T.  .1.  Twomey,  •/.  Phys.  Chem., 
1916,  p.  121.  2  See  C.  F.  Chandler,   ibid.,  p.  76. 


BY-PRODUCTS   OF   COAL   DISTILLATION  251 

Thus  not  only  is  the  soda  saved  and  used  again  but  the  carbolic  acid  remain- 
ing in  the  solution  passes  into  the  process  again.  The  crude  phenol  separates 
as  an  upper  layer  on  the  acidified  liquor  :  it  is  drawn  off  and  further  purified 
by  fractionating  through  a  dephlegmating  column.  At  first  the  distillate 
consists  of  water  containing  only  a  small  percentage  of  phenol,  then  practically 
pure  phenol  comes  over  ;  x  at  the  end  of  the  distillation  cresols  are  obtained. 
The  phenol  can  be  further  purified  by  allowing  it  to  crystallize  and  pressing 
out  the  liquid  residue. 

Cresol  can  be  separated  and  in  a  similar  manner  from  the  fractions  from 
which  the  phenol  has  already  been  removed,  and  it  can  be  purified  in  the 
same  way.  But  as  a  rule,  cresol  and  the  other  similar  bodies  are  used  with- 
out exhaustive  purification  for  the  preparation  of  disinfectants,  etc.  The 
alkaline  washings  obtained  by  treating  benzol  with  caustic  soda  solution  are 
worked  up  for  phenol  or  crude  carbolic  acid  in  the  same  way. 

Before  the  war  Germany  depended  largely  on  England  for  the  supply 
of  carbolic  acid,  as  the  coke-oven  tars  made  there  contain  comparatively 
little  of  it,  and  its  extraction  consequently  could  not  compete  very  success- 
fully with  the  English  product  made  from  gas  tar.  For  the  rectification  of 
the  carbolic  oil  from  coke-oven  tar,  F.  Raschig  recommends  that  it  be  frac- 
tionated in  vacuo  through  a  very  tall  dephlegmating  column,  14  metres  long. 
This  column  he  fills  with  small  hollow  rings  of  sheet  iron,  1  inch  long  and  1 
inch  in  diameter,  with  walls  of  J^  mcn  thick.  These  offer  a  very  large 
surface  for  the  interaction  of  the  vapour  and  condensed  liquid,  and  conse- 
quently improve  the  fractionation  and  offer  little  resistance  to  the  passage 
of  the  vapours,  and  so  do  not  diminish  the  vacuum.  The  distillation  is 
carried  out  at  about  120°  C.  At  first  an  oil  passes  over  containing  no  phenol, 
and  is  shown  by  the  fact  that  if  a  portion  be  shaken  with  caustic  soda  its 
volume  is  not  reduced.  After  a  time  the  phenol  content  rises  rather  suddenly 
to  30  or  40  per  cent.  It  remains  at  this  for  some  time,  and  then  falls  to  20 
or  25  per  cent.,  and  naphthalene  then  crystallizes  out  from  the  distillate  on 
cooling.     The  distillation  is  now  stopped. 2 

When  the  demand  for  phenol  is  so  great  that  it  cannot  be  met  by  the  Phenol  fro 
amount  obtained  from  coal  tar,  the  consequent  rise  in  price  makes  it  remu- 
nerative to  manufacture  phenol  from  benzene  by  sulphonation  and  fusion  with 
soda.  A.  H.  Ney  has  described  the  process  with  considerable  detail  in  a 
lecture3  in  New  York  :  the  following  description  gives  the  methods  briefly. 
The  sulphonation  kettle  is  a  cast-iron  vessel,  fitted  with  a  lid  and  a  condenser 

1  For  the  vapour  pressures  of  mixtures  of  phenol  and  water  see  F.  A.  H.  Schreine- 
makers,  Proc.  K.  Akad.  Wetensch.,  Amsterdam,  1900,  p.  1  ;  also  A.  Marshall,  J.  Chem. 
Soc,  Trans.,  190G,  p.   1365.  2  Aug.,  1915,  i.  p.  409. 

3  Reproduced  in  Ch em.  Trade  Jour.,  October  16  and  23,  1915;  also  Met.  and  Chem. 
Eng.,  1915,  p.  686. 


►52 


EXPLOSIVES 


Naphthalene. 


Yields. 


to  condense  vapour  of  benzene  and  retain  it  to  the  kettle.  It  has  a  good  stirrer 
and  a  jacket  for  heating  it.  Eight  parts  by  weight  of  concentrated  sulphuric 
acid  are  placed  in  it.  and  three  parts  of  benzene  are  added  with  constant 
Btirring.  When  the  temperature  ceases  to  rise,  heat  is  applied  and  it  i>  main- 
tained near  the  boiling-point  of  benzene.  After  five  to  nine  hours  the  sul- 
phonation  is  complete  and  the  contents  of  the  kettle  are  run  into  a  lead-lined 
tank  and  diluted  with  an  equal  volume  of  water.  Then  milk  of  lime  is  added. 
which  converts  the  benzene  Bulphonic  acid  into  the  calcium  salt,  which 
remains  in  solution,  and  the  excess  of  sulphuric  aeid  into  ealeium  sulphate, 
which  i-  precipitated.  The  latter  is  filtered  off  in  a  filter  pre>s  ami  washed  : 
the  solution  is  mixed  with  sodium  carbonate  (soda  ash),  which  precipitates 
the  ealeium  as  carbonate  and  leaves  sodium  sulphonate  in  solution.  This  is 
evaporated  down  and  the  dry  salt  is  heated  with  fused  caustic  soda.  In  a 
cast-iron  vessel  are  placed  10  parts  of  caustic  soda  and  a  little  water.  This 
i-  melted  and  heated  to  about  27o  .  and  10  parts  of  the  sulphonate  are  gradu- 
ally added.  The  temperature  is  then  raised  to  about  315'  :  the  Bulphonate 
i-  thus  converted  into  -odium  phenate  and  sulphite 

C6H  ,S(  ),Xa  4-  2XaOH  =  C6H5OXa  -f  Xa  2S03  -f  H.O. 
The  melt  is  ladled  out.  allowed  to  solidify,  broken  up,  crushed  and  dissolved 
in  water.  Then  dilute  sulphuric  acid  is  run  in  until  there  is  a  copious  evolu- 
tion of  sulphur  dioxide,  and  the  liberated  phenol  is  allowed  to  separate  out. 
It  is  freed  from  sulphur  dioxide  by  blowing  air  through,  and  i-  rectified  by 
distillation. 

The  naphthalene  which  crystallizes  out  from  the  carbolic  oil  and  various 
other  fractious  is  subjected  to  a  number  of  operations  to  purify  it.  After 
allowing  it  to  drain  it  is  heated  and  pressed  in  a  powerful  press  to  ren 
the  bulk  of  the  oil.  Then  it  i>  washed  with  caustic  soda  solution  to  dissolve 
out  carbolic  acid,  and  then  with  hot  water.  Xext  it  is  heated  with  sulphuric 
acid  of  about  1-8  specific  gravity,  which  absorbs  various  impurities.  Then 
it  i<  washed  again  with  hot  Mater,  and  afterwards  with  weak  alkali,  and 
finally  it  is  fractionally  distilled.  It  is  thus  obtained  a-  a  white  crystalline 
-■lid   having  a   characteristic  smell. 

The  quantities  of  the  different  products  obtained  naturally  vary  accord- 
ing to  the  nature  of  the  tar  and  the  proot  3S<  -  lopted,  but  they  are  usually 
within  the  following  limits  :  1 

Benzene  and  toluene     .  .  .  .  .  1  to   1-5  ]><t  cent. 

Anthracene  ........  0-25  i"  0-45  .. 

Phenol <>4  to  •'•;, 

ml 2  to     3 

Naphthalene  .         .         .         .         .  6  to   1" 

Eleavy  oil     .         .         .         .         .         .         .  -2~>  !•  i  :;<• 

Piteh 50  to 

1  M eyer  und  Jaoobeon,  Chemie,  vol.  ii.  pari  L,  p.93. 


CHAPTER   XIX 

NITRO-DERIVATIVES   OF   AROMATIC   HYDROCARBONS 

Nitro-benzene  C6H5N02  :  Accidents  :  Dinitro-benzene  C6H4(N02)2  :  Trinitro- 
bonzene,  C6H8(N02)3  :  Nitro -toluene,  C7HTX02  :  Dinitro -toluene,  C7H6N204  : 
Trinitro-toluene,  C'THiX30G  :  Waste  acids  :  Purification  of  trinitro-toluene 
The  trinitro-toluenes  :  Accidents  :  Properties  :  Density  :  Mono-nitro-naphthalene, 
Cui'H^XO* :  Dinitro-napbthalene,  C10H6N2O4  :  Trinitro-naphthalene,  CMH5N808  : 
Tetranitro-naphthalene,  C  10H4N4Os 

Benzene  is  nitrated  on  a  very  large  scale  as  a  stage  in  the  manufacture  of  Nitro-benzem 
aniline,  which  is  used  in  the  preparation  of  many  dye-stuffs.  The  process 
of  nitration  does  not  differ  in  principle  from  the  manufacture  of  nitro-glycerine, 
but  the  mixed  acids  are  generally  run  into  the  benzene  instead  of  the  benzene 
into  the  acids,  and  as  mono-nitrobenzene  is  not  explosive,  the  same  precautions 
are  not  necessary.  Fig.  51  shows  a  plant  capable  of  nitrating  500  gallons 
or  two  tons  of  benzene  in  one  charge.  It  consists  of  a  cast-iron  pan  F  having 
a  total  capacity  of  1600  gallons.  It  has  a  strong  lid,  through  which  passes 
a  shaft  bearing  the  two  propeller  agitators  H,  the  lower  of  which  is  surrounded 
by  a  cylinder  to  increase  the  upward  motion  of  the  acid.  On  the  top  of  this 
cylinder  is  a  grid  K  supporting  the  lead  coils  J,  the  inlets  of  which  are  shown 
at  N,  0,  and  the  outlets  at  L,  M.  These  coils  are  each  2  inches  in  diameter, 
and  150  feet  long.  Through  these  cooling  water  can  be  circulated,  or  hot 
water  or  steam  if  it  be  required  to  raise  the  temperature  of  the  contents  of 
the  pan.  Into  the  acid  mixing  tank  A  are  run  5000  lbs.  of  nitric  acid  of  specific 
gravity  1-43  through  the  pipe  D,  and  through  G  6600  lb.  of  concentrated 
sulphuric  acid.  They  are  then  mixed  together  by  blowing  air  through  the 
perforated  pipe  B  ;  but  in  some  works  large  rpiantities  of  acid  are  mixed  at 
a  time  in  capacious  tanks  and  allowed  to  settle.  The  benzene  is  introduced 
into  the  pan  and  the  agitators  are  revolved  at  about  60  revolutions  per  minute, 
and  then  the  acid  is  run  in  in  a  thin  stream,  the  temperature  not  being  allowed  to 
rise  above  60° C.  After  the  whole  of  the  acid  has  been  introduced,  agitation 
is  continued  for  a  further  4|  hours  to  complete  the  nitration.  The  waste 
acid  should  then  contain  less  than  1  per  cent,  of  nitric  acid.  The  contents 
of  the  pan  are  then  allowed  to  settle,  and  the  waste  acid  is  run  into  the  egg 
X,  and  blown  up  through  the  pipe  V  to  the  waste  acid  tank  by  admitting  com- 
pressed air  through  U.  The  nitro-benzene  is  similarly  run  into  X,  and  blown 
up  through  the  pipe  S  into  the  wash-pan  B,  where  it  is  washed  first  with 

253 


EXPLOSIVES 


soda  solution  and  then  with  water,  air  being  blown  in  through  the  pipe  P  to 
agitate  the  liquids.  After  settling,  the  nitro-benxene  ifi  run  to  a  storage  tank. 
The  maximum  theoretical'yield  from   101  .f  benzene  is  157-6,  and  the 


51. 


i;>inmiWjiiwmi^i  ii  miiiMj.mmuji  fuM'ni"i'M     lunninini 
Benzene  Nitrating  Plant.      (From  TL'  ::  •   -  Dick  Oltarff  'ry) 


actual  yield  should  not  be  le>>  than  154-5.  The  nitrobenzene  can  be  further 
purified  by  distillation  in  vacuo. 

Nitrobenzene   <    H  V  •      -  yellow  oil  slightly  volatile  at  the  ordin- 

ary temperature  and  having  a  characu-ri-tk-  odour.  It  is  slightly  poisonous, 
but  is  used  for  perfumery  and  flavouring  under  the  name  of  "  oil  of  mirhane." 
Under  atmospheric  pressure  it  h  _  b  freeses  with  i  me  difficulty. 


NITRO-DERIVATIVES   OF  AROMATIC  HYDROCARBONS      255 

and  melts  at  3-6°.  Although  its  use  has  often  been  proposed  as  an  ingre- 
dient of  various  explosives  it  has  not  been  so  used  very  extensively,  as  its 
volatibility  is  objectionable,  and  there  are  other  nitro-compounds  available 
which  have  more  decided  explosive  properties.  It  has,  however,  been  used 
as  an  ingredient  of  Sprengel  explosives  and  to  reduce  the  freezing-point  of 
nitro-glycerine.  It  is  practically  insoluble  in  water,  but  soluble  in  alcohol 
ether  and  other  organic  solvents. 

With  ordinary  care  the  nitration  of  benzene  is  quite  a  safe  operation,  Accidents, 
but  in  February  1914,  there  was  a  severe  accident  at  Rummelsburg  in  the 
works  of  the  Aktiengesellschaft  fur  Anilinfabrikation  whereby  eleven  people 
were  killed  and  fourteen  injured.  The  catastrophe  seems  to  have  been  caused 
by  allowing  the  acid  to  run  into  the  benzol  without  starting  either  the  stir- 
ring gear  or  the  cooling  water.  After  a  time  such  an  energetic  action  set  in 
that  the  top  was  blown  off  the  pan,  and  large  quantities  of  benzol  vapour 
escaped,  mixed  with  the  air  and  exploded.  Similar  accidents  occurred  at 
Mannheim  in  1907,  and  Moscow  in  1911. 

After  the  Rummelsburg  catastrophe  a  committee  of  chemical  manufac- 
turers assembled  in  Wiesbaden  to  consider  the  steps  to  be  taken  to  avoid 
the  recurrence  of  such  accidents,1  and  subsequently  the  Prussian  Minister 
for  Trade  and  Industry  passed  regulations  somewhat  similar  to  those  in 
force  in  explosives  factories,  namely  : 

1.  Accumulations  of  material  and  persons  are  to  be  avoided  as  far  as 
possible. 

2.  Arrangements  must  be  made  to  prevent  large  quantities  of  raw  materials 
interacting  on  one  another  at  one  time.  The  nitration  plant  should  be  exam- 
ined every  time  before  it  is  started  ;  accidents  may  be  caused  by  the  inad- 
vertent presence  of  acid. 

3.  It  is  undesirable  that  the  plants  should  be  in  communication  with 
one  another. 

4.  The  nitrators  are  to  be  so  erected  that  if  large  volumes  of  hydrocarbon 
vapours  are  evolved  they  Mill  be  discharged  above  the  roof  by  an  outlet  of 
sufficient  size. 

5.  Arrangements  must  be  made  that  acid  cannot  be  run  in  before  the 
stirrer  has  been  started. 

6.  There  must  be  a  device  to  show  whether  the  Liquid  is  in  motion. 

7.  These  rules  may  be  moderated  somewhat  in  the  case  of  continuous 
processes. 

At  the  meeting  of  the  Wiesbaden  Committee,  W.  ter  Meer  described  a 
continuous  nitration  plant,  which  he  has  used  in  his  works.2  This  consists 
of  a  cylindrical  vessel  of  3  cubic  metres  capacity  provided  with  two  inlets 
at  the  bottom  end  for  benzol  and  acid  respectively.     Down  the  middle  of 

i  Chem.  Ind.,  1914,  p.  337.  2  Germ.  Pat.  228,544  of  July  24,  1909. 


256  EXPLOSIVES 

the  cylinder  passes  an  axle  carrying  a  number  of  stirrer  blades.  The  path 
of  the  liquid-  is  prolonged  by  a  number  of  diaphragms  extending  nearly 
acros-  the  cylinder  and  fixed  alternately  to  the  walls  and  t<>  the  axle.     The 

cylinder  is  provided  with  a  water-jacket  and  an  outlet  at  the  top.  The  benzol 
i-  introduced  at  the  rate  "f  •■J1"1  kg.  per  hour,  together  with  the  requisite 
quantity  of  mixed  arid,  about  s<>o  litre-  in  all.  They  take  nearly  four  hours 
to  pass  through  the  nitrator,  and  in  a  twelve-hour  shift   i  f  good  nitro- 

benzol  are  obtained. 

Neumann  described  a  similar  plant  in  which  the  reacting  liquids  are  made 
to  traverse  an  annular  space  between  a  fixed  and  rotating  cylinder,  both 
carrying  stirrer  blades  and  cooled  or  heated  locally  or  entirely  as  required. 

Kubierschfcy's  plant  is  on  a  different  system  :  it  has  no  mechanical  stirrers 
and  the  benzol  and  acid  are  made  to  pass  in  opposite  directions  through  a 
lower.  It  is  shown  diagrammatic-ally  in  Fig.  ~>2.  The  benzol  flows  from  the 
tank  A  into  the  nitrating  tower  I  at  the  point  a  near  the  bottom.  The  mixed 
acid  Mows  from  B  into  the  same  tower  near  the  top  at  h  :  in  consequence 
of  its  higher  gravity  it  sink-  down  gradually,  nitrating  the  benzol  as  it  g  be 
At  the  bottom  of  the  tower  the  waste  acid  separates  from  the  benzol  and  flows 
into  the  tank  G.  The  nitrated  product  flows  from  the  top  of  the  tower  through 
the  pipe  d.  and  the  visible  overflow  D  to  the  washing  tower//,  where  it  meets 
a  stream  of  water  flowing  up  the  tower,  and  is  thus  freed  from  acid.  The 
How  from  the  bottom  of  //  is  regulated  by  the  cock  e:  the  nitro-benzol  is 
preheated  in  E.  and  then  flow-  at  /into  the  top  of  the  column  ///.  Up  to 
this  point  the  nitro-benzol  contains  about  1<>  per  cent,  of  unchanged  benzol. 
an  excess  having  been  used  to  prevent  the  formation  of  dinitro-benzol.  In 
///  this  benzol  is  removed  by  means  of  live  steam  at  g.  The  purified  nitro- 
benzol  then  flows  through  the  cooler G,  and  the  visible  overflow  to  the  separator 
A*,  where  it  is  freed  from  water,  carried  along  mechanically.  The  distillate 
from  ///  is  condensed  inEandF.  and  is  separated  in  J  into  benzol  and  water. 

The  construction  of  column  /  is  shown  in  Fig.  53.  The  arrows  in  the 
Lower  portion  show  the  way  the  benzol  circulates  and  passes  in  a  finely  divided 
state  through  the  acid  which  is  moving  in  the  opposite  direction.  The  nitric 
acid  i-  thus  very  fully  utilized.  The  temperature  in  this  column  is  regulated 
by  means  of  the  coils.  The  nitration  process  is  followed  by  taking  readings 
of  the  density  of  the  crude  nitro-benzol  by  a  hydrometer  in  D.  and  the  flow 
of  benzol  and  acid  is  regulated  accordingly.  The  column  //  is  of  similar 
construction  to  /.     This  plant  is  said  to  work  well. 

Dinitro-benzene  is  manufactured  in  the  same  way  as  mono-nitro-benzene. 

pt   that   twice  as  much  acid  is  used.     The  nitration  is  generally  carried 

out  in  two  stages,  the  bulk  of  the  waste  acid  from  the  first  stage  being  run 

away   lief.. re  the  second   lot    is  run  in.      For  the  second  stage  the  acids  may 

with  advantage  be  somewhat  stronger  and  the  content-  of  the  nitrating  pan 


NITRO-DERIVATIVES   OF  AROMATIC   HYDROCARBONS    257 


are  heated,  finally  to  near  the  boiling-point  of  water.  The  waste  acid  from 
the  second  stage  may  be  revivified  by  the  addition  of  strong  nitric  acid  and 
used  for  the  preliminary  nitration  of  a  further  charge  of  benzene.  Of  the 
three  isomeric  dinitro-benzenes  the  meta-compound  is  that  principally  formed, 
mixed  with  only  small  quantities  of  ortho-  and  para-dinitro-benzene.     It  is 


I       Ni+robeni 


Benzoh    J-    I   fatef        fofrJ    ft  hrft 


Fig.  52.     Kubierschky's  Nitrating  Plant. 


Fig.  53.     Kubierschky's  Nitrating  Tower. 


separated  from  the  waste  acid  and  washed  first  with  cold  water,  and  then 
with  hot.  As  it  is  slightly  soluble  in  the  latter,  the  final  wash- water  should 
be  kept  and  used  again  for  the  cold  washing  of  a  later  charge. 

Pure    m-dinitro-benzene    melts    at    89-9°,    whereas    the    melting-points 
of  the  o-  and  p-compounds  are  118°  and  172°  respectively.     Good  commercial 
dinitro-benzene  melts  at  85°  to  87°,  and  is  in  the  form  of  long  shining  needles 
vol.  i.  iy 


25S 


EXPLOSIVES 


Tt.z.t:- 
C,H    SO. 


of  light  yek  nr.     It   should  contain  no  nitrobenzene  and  should  be 

odourless.  It  is  readily  soluble  in  alcohol,  benzene  and  other  organic  solvent, 
and  can  be  purified  by  recrystallization  from  them.  It  can  only  be  detonated 
with  great  difficulty,  and  consequently  is  not  used  an  an  explosive  by  itself, 
but  it  has  been     -  stituent  of  complex  explosives,  such    as    the 

ammonium  nitrate  explosive  s,  Belhte  and  Roburite,  and  low  freezing  nitro- 
glycerin- There  has  been  a  tendency  of  recent  years  to  substitute 
di-  and  tri-nitro-toluene  for  this  substance,  but  the  present  scarcity  of  toluene 
is  likely  to  cause  this  practice  to  be  reversed.  The  density  of  m-dinitro- 
benzene  is  1  30           8     1°. 

By  a  further  nitration  of  dinitro-benzene  it  can  he  converted  partly  into 
trinitro-benzene.  but  it  is  necessary  to  use  very  strong  acids  made  with  oleum,' 
and  to  cany-  out  the  nitration  at  a  high  temperature  and  for  a  long  time. 
This  drastic  treatment  causes  the  destruction  of  much  of  the  material  by 
oxidation,  and  consequently  the  yield  is  poor.  It  is  obtained  more  easily 
from  trinitro-toluene  :  this  is  oxidized  by  sulphuric  acid  and  bichromate 
of  potash  to  trinitro-benzoic  acid,  which  is  reduced  to  trinitro-benzene  by 
boiling  with  water.  In  either  case  the  manufacture  is  expensive  and  trouble- 
some, so  that  although  it  is  a  slightly  more  powerful  explosive  than  either 
trinitro-toluene  or  picric  acid  it  has  never  come  into  general  use. 

There  are  three  possible  trinitro-benzene.-.  but  the  one  that  is  obtained 
almost  exclusively  is  the  symmetrical  or  1  :  3  :  5  compound. 

NO, 


NO, 


m 


It  melt>  at  121  ts  <  a  we  properties  have  been  investigated  by  Daut- 

riche.1     The  1:2:4  compound  is  also  known. 
»tootoinene.         Toluene  is  nitrated  in  the  same  way  as  benzene,  but  the  nitration  pro- 
c  H"*0:         ceeds  somewhat  more  rapidly  :    als         -  -     equired  because  the  mole- 

cular weight     -  g      -  Of  the  three  nitro-tomenes  only  *  to  4  per  cent, 

of  the  meta-compound  is  formed,  about  3s  per  cent,  of  the  para  and  60  per 
cent,  of  the  ortho.  the  proportions  varying  somewhat  according  to  the  con- 
ditions of  nitration.2  The  yield  is  about  14<i  parts  from  LOO  parts  of  toluene. 
whereas  according  to  theory  there  should  be  140.  The  product  has  a  specific 
gravity  of  about  11 65.  and  is  liquid  at  the  ordinary  temperature.  By  cool- 
_  it  to  about  1"   <  ..part  of  the  para-nitro-toluene  can  be  mad  irate 

out  and  filtered  off  on  a  cooled  filter  plate,  but  to  effect  a  separation  of  the 

1  r 

-    -       A.  F.  Holleman.  Proc  K.  Abad.   H  1908*  voL  xi.,  p.  248; 

far  1  •  p.  1.     EL  W.  Kb  :.■  r,Z.  Ekktroc..  1910,  p.  161. 


NITRO-DERIVATIVES   OF   AROMATIC   HYDROCARBONS       259 

constituents  of  the  liquid  residue  it  is  necessary  to  submit  it  to  fractional 
distillation  in  vacuo.  The  ortho-compound  distils  over  first ;  when  the 
greater  part  of  it  has  passed  over  the  distillation  is  interrupted  and  the  residue 
is  run  out  and  cooled,  whereupon  it  deposits  the  greater  part  of  its  para- 
nitro-toluene.  The  following  are  the  principal  physical  properties  of  the 
nitro-toluenes  : 

Meta 


ell 


UNo* 


NO. 


Specific  gravity  1-163  (20°/4°)  1-168(22°)  1123(54°) 

Melting-point  —3-85°  +16-1°  52° 

Boiling-point  223-3  230-231  237-7 

The  mono-nitro-toluenes  are  not  explosive  in  themselves  and  are  not  used 
as  constituents  of  composite  explosives,  but  they  are  formed  in  the  first  stage 
of  the  formation  of  di-  and  tri-nitro-toluenes,  and  para-nitro-toluene  is  used 
extensively  for  the  manufacture  of  dye-stuffs. 

On  further  nitration  para-nitro-toluene  gives  almost  exclusively  2  :  4-  Dinitro- 
dinitro -toluene,  and  the  ortho-derivative  gives  mostly  the  same  compound,  o7Hjr.b 
but  also  some  2  :  6-dinitro-toluene.  The  meta-derivative  is  present  only  in 
small  quantity  and  nitrates  much  less  readily,  and  consequently  remains 
unchanged  to  a  considerable  extent.  Consequently  the  principal  product  of 
the  direct  nitration  of  toluene  to  the  second  stage  is  2  :  4-dinitro-toluene  mixed 
with  small  quantities  of  other  dinitro-compounds,  some  mono-nitro-toluene 
(meta  and  para)  and  trinitro-toluene.  The  mono-nitro-toluenes  are  only 
separated  from  one  another  before  nitration  if  the  para-compound  is  required 
for  the  manufacture  of  dye-stuffs  ;  in  this  case  the  crude  ortho-nitro-toluene 
is  taken  for  nitration.  When  the  nitration  is  complete  the  crude  dinitro-toluene 
is  allowed  to  separate  from  the  waste  acids  in  the  warm.  On  cooling  it  sets 
to  an  oily  solid.  This  is  often  purified  by  warming  it  to  about  40°  C.  and  allow- 
ing the  more  easily  fusible  portion  to  flow  away.  The  purified  product  is 
used  for  the  manufacture  of  dye-stuffs,  and  sometimes  for  the  preparation  of 
composite  explosives  such  as  Cheddite.  The  more  fusible  residue  is  known 
in  Germany  as  "  Binitrotropfol,"  and  is  used  for  the  manufacture  of  trinitro- 
toluene. From  the  waste  acids  on  cooling  there  separates  out  a  further  small 
quantity  of  nitro-product  which  floats  on  the  surface,  from  which  it  is  skimmed 
off.  The  waste  acid  has  a  specific  gravity  of  1-75  to  1-77,  and  contains  from 
3  to  4  per  cent,  of  nitric  acid,  whereas  the  waste  acid  from  the  manufacture 
of  mono-nitro-toluene  has  a  specific  gravity  of  1-66  to  1-67,  and  contains, 


260  EXPLOSIVES 

according  to  R.  Escales,  1  to  1*5  per  cent,  nitric  acid.1  If  the  nitration  l>c 
properly  conducted  the  yield  of  dinitro-toluene  is  not  far  Bhorl  of  the  theo- 
retical. 

There  are  six  possible  dinitro- toluenes, and aU  of  them  have  been  prepared 
either  by  nitration  of  toluene  or  by  more  indirect   methods. 


I  II 


Xi), 


NO,      I     JNO.,  k     )         NO 


CH, 

Ano, 

II 

\/     N,,J 

\y 

NO, 

2:5                    3:5 

52-5°                9 

1  93 

o 

NO  NO, 

2:4  3:4 

Melting]  70o  GOo 
point     i 

( tf  these  the  firsl  is  the  only  one  that  is  of  any  commercial  importance  :  ortho- 
nitro-toluene.    however,  gives   a   little   of   the   2  :  6-compound.      Meta-nitro- 

toluene  gives  3  :  -4  mixed  with  smaller  quantities  of  2  :  3  and  3  :  6.'     ( 'ommer- 
cial   crude  dinitro-toluene  contains,  therefore,  all  the  above  six  compounds 

ept  the  last,  but  the  first  predominates.  The  statement  that  the  3:5- 
derivative  is  also  formed3  is  doubted  by  Will.4  All  except  the  2:3-  and 
3  :  5-compounds  have  been  found  in  a  by-product  from  the  purification  of 
dinitro-toluene.5 

In  explosive  properties  all  these  substances  are  very  similar:  they  can 
only  be  detonated  with  great  difficulty,  and  are  decidedly  insensitive.  The 
2  :  4-compound  is  used  as  a  constituent  of  composite  blasting  explosives. 
notably  chedditc.  They  possess  the  disadvantage  that  they  are  very  poisonous 
and  are  liable  to  affect  injuriously  those  who  handle  them.  From  the  purifi- 
cation of  the  crude  material  a  complex  mixture  can  be  obtained,  which  is 
liquid  at  the  ordinary  temperature.  This  dissolves  collodion  cotton,  and 
i-  thereby  converted  into  a  thick  jelly,  which  is  used  in  the  manufacture  of 
plastic  blasting  explosives. 

Trinitro-toluene  may  be  made  by  the  nitration  either  of  "  Binitrotropfol  " 
or  crude  ortho-nitro-toluene  or  from  toluene  by  successive  nitration  in  two 
or  three  stages  without  the  separation  of  any  of  the  nitro-bodies.  In  any  case 
it  i-  best  to  conduct  the  conversion  of  di-  into  tri-nitro-toluene  as  a  separate 
operation  a-  it  requires  a  stronger  mixed  acid,  and  if  a  large  volume  of  strong 
mixed  acid  lie  used  to  nitrate  toluene  or  mono-nit ro-toluene  directly  to  trinitro- 

1  Nitroaprengstoffe,  p.   1 12. 

2  A.  F.  HoUeman  and  EL  A.  Sirks,  Proc.    K.    Akad.    Wetenach.,  Amsterdam,   L906, 
p.  280;    Chem.  See.  Abstr.,   1907,  i.,  p.  280. 

3  Hauaeermann  and  Grell,  Ber.,   1895,  p.  2564  4  Ber.,  1913,  p.  558. 

"•  E.  MoUnari  and  M.  Giua,  Bendiconti  del  Bealt  letituto  di  8rten&  •  Lettere,  1913,  voL 
46,  No.   11  ;    S.S..    l'.»14.  p.   239. 


NITRO-DERIYATIYES   OF  AROMATIC  HYDROCARBONS     261 

toluene  the  yield  will  be  low  in  consequence  of  its  solubility  in  the  waste  acid, 
and  by-reactions  due  to  the  oxidizing  action  of  the  acid.  The  mixed  acid 
may  be  made  by  adding  nitric  acid  cautiously  to  oleum  of  20  per  cent,  strength. 
According  to  F.  Langenscheidt  the  quantities  are  1125  kg.  of  20  per  cent, 
oleum  and  305  kg.  nitric  acid  of  sp.  gr.  1-5.1  500  kg.  of  binitrotropfol  are  placed 
in  the  nitrating  pan  and  melted  and  the  mixed  acid  is  run  in  slowly  at  a  tem- 
perature of  70  to  75°  C.  When  all  the  acid  has  been  added  the  mixture  is 
warmed  gradually  until  at  90°  to  100°  the  reaction  sets  in  and  the  tempera- 
ture rises  to  about  130°.  At  this  temperature  it  is  allowed  to  remain  for 
an  hour  and  then  cooled  to  100°.  Water  is  added  to  the  charge  to  diminish 
the  solubility  of  the  trinitro-toluene  in  the  acid,2  and  the  contents  of  the 
nitration  are  run  off  through  a  steam-heated  cock  and  kept  hot  until  separa- 
tion is  complete.  The  trinitro-toluene  may  be  solidified  in  a  suitable  state 
of  division  by  running  it  on  to  a  jet  of  air  over  water.  Toluene  is  nitrated 
with  considerably  greater  ease  than  benzene,3  but  it  is  necessary  to  use  strong 
acids  at  a  high  temperature  to  make  the  trinitro-derivative,  and  there  is  an 
appreciable  loss  by  oxidation,  with  the  result  that  the  yield  is  lower  than 
the  theoretical.  According  to  Will  trinitro-benzoic  acid  and  tetranitro- 
methane  are  liable  to  be  formed,4  the  latter  may  sometimes  be  recognized 
in  the  factory  by  its  intense  smell.  The  oxidizing  action  is  said  to  be  increased 
by  the  presence  of  metallic  salts,5  sodium  nitrate,  and  especially  ammonium 
nitrate.0  but  the  formation  of  nitro-benzoic  acid  under  manufacturing  condi- 
tions has  been  denied  by  F.  Langenscheidt.7  According  to  Copisarow,  phenolic 
compounds  are  liable  to  be  formed  by  the  action  of  the  acids  on  the  metal 
of  the  nitration  vessel  producing  hydrogen,  and  sulphonic  acids  if  the  quan- 
tity of  nitric  acid  present  be  insufficient. 

The  waste  acid  contains  up  to  4-5  per  cent,  of  nitric  acid  and  nitrous  Waste  acids. 
acids,8  and  a  considerable  amount  of  trinitro-toluene  and  various  by-pro- 
ducts in  solution.  It  may  with  advantage  be  revivified  and  used  for  the 
manufacture  of  mono-or  di-nitro-toluene,9  or  the  nitric  acid  is  distilled  off 
after  diluting  to  density  of  1-38,  and  the  residue  is  further  diluted  to  1-21 
to  precipitate  the  nitro-bodies.  It  is  not  advisable  to  use  the  waste  acid  for 
the    manufacture    of   nitric    acid    from    sodium    nitrate    because    the    nitro- 

1  S.S.,    1912.   p.   42:.. 

2  S&  Germ  Pat.  254,754  of  July  L5,  L 909,  also  Vermin  et  Chesneau,  p.  261. 

:1  For  measure  ments  of  the  vel<  cities  of  nitration  see  .!.  J'.  Wibaut,  Rec.  Trav.  chim., 
1915.  ]>.  950;    J.  Soc.  Chem,  /,.,/.,  1915,  p.  241.  ■  /;,,■..   L914,  p.  707. 

5  M.  Copisarow,  Chem.  News,  1915,  vol.  112,  p.  247;  J.  Soc.  Chem.  Ind.,  1915,  p.   lliiS. 

'■  A.  Voigt,  S.S.,   1914,  p.  225.  <  S.S.,   1915,  p.  23. 

5  Set    L.  Wuyts,  ./.  Soc.  Chem.   Ind.,   1916,  p.   149. 

9  Set  I'.  M.  Vasquez,  Memorial  dt  AriiUeria,  Sept.  1910;  S.S.,  1911,  p.  302!  also 
Eng.  Pat.  23,181  of  1914,  byCraig,  Robertson,  Farmer  and  Rotter,  Arms  and  Explosives 
L915,  p.   L39. 


262 


EXPLOSIVES 


explosiv*  -  3&  unaltered  into  the  nitro-cake  and  may  cause  explosions.1 
Or  it  may  be  denitrated  in  a  denitration  tower,  1  »\it  in  tlri>  case  a  large  pro- 
portion of  the  nitro-oompounda  ]>a>>  over  with  the  nitrous  _ 
stoppages.'  The  following  are  the  compositions  of  two  waste  acids  dven 
by  y\.  I  bpisaroff  :  3  in  the  second  one  an  insufficient  quantity  of  nitric  acid 
has  been  used  : 


Colour 

yellow 

brown 

Nitxous  acid 

. 

•  ' 

Nitric  acid    . 

. 

0 

Sulphuric  acid 

.      i. 

580 

Water  .... 

.     34-29 

Sulphonic  acids 

0 

4-72 

too 


too 


W.  McHutchison  and  R.  Wright4  give  the  following  as  the  composition 
of  a  waste  acid  : 


Colour 

Nitrous  acid 
Nitric  acid 
Sulphuric  acid 
Water,  etc. 

Specific  gravity. 


brown 

0-50 
6-71 

G-49 

1-850  at    17° 


On  mixing  with  this  an  equal  volume  of  water,  reducing  the  specific  gravity 
to  1.4s!t.  trinitro-toluene  separated,  equivalent  to  5*8  per  cent,  by  weight. 
The  addition  of  4  more  volume-  of  Mater  only  increased  this  amount  to 
6*2  per  cent.  The  authors  recommend  that  the  waste  acid  be  added  to  the 
water,  and  not  vice  versa,  bo  as  to  recover  the  trinitro-toluene  in  a  convenient 
form . 

The  nitro-compounds  can  also  be  extracted  from  the  waste  acid  by  agitating 
it  with  toluene,  or  by  revivifying  the  acid  and  using  it  for  the  manufacture 
of  mono-  or  dinitro-toluene.     In  either  case  the  toluene  used  to  extract  the 
nitro-body  is  eventually  converted  into  trinitro-toluene. 
Purification  of        The  crude  product  is  freed  from  acid  either  by  boiling  it  with  water  or  by 
trinitro-  washing  it  in  a  granular  condition  with  warm  water  with  the  addition  of  a 

little  sodium  bicarbonate.  It  is  then  dried  and  purified  either  by  washing 
with  alcohol  of  95  per  cent,   strength/  or  by  llization  either  from 

alcohol  or  benzene.     According  to  Langenscheidt.6  technical  alcohol  contain- 

1  Vennin  <t  Cheaneau,  j>.  -  -  1      Langenscheidt,  >'.>"..   1912,  j>.  12 

3  Chan.  .v.    -.   L91S,  p.  247:    ./.  Soc  Chem.  Ind.,  1915,  1168. 

«  J.   -       <    em.  Ind.,  1916,  p.  781. 

6  Vennin  et  Cheaneau,  p.  261.  6  >'.>'.,   1912,  p.  427. 


NITRO-DERIVATIVES   OF  AROMATIC  HYDROCARBONS      263 

ing  about  90  per  cent.  C2H5OH  dissolves  at  the  boiling-point  one-ninth  of  its 
weight  of  trinitro-toluene  and  gives  90  per  cent,  of  it  up  again  on  cooling. 
Benzene  dissolves  1-7  times  its  weight  at  the  boiling-point,  and  about  78  per 
cent,  of  it  crystallizes  out  again  on  cooling.  But  the  best  solvent  is  alcohol 
mixed  with  5  to  10  per  cent,  of  pure  benzene.  In  a  double- walled  iron  vessel 
are  placed  2300  litres  of  this  solvent,  and  500  kg.  of  trinitro-toluene.  The 
liquid  is  stirred  and  boiled,  the  vapour  formed  being  condensed  and  returned 
to  the  vessel.  When  solution  is  complete  the  liquid  is  filtered  and  allowed 
to  cool.  The  crystals  are  freed  from  mother  liquor  by  centrifuging  or  filter- 
ing off  in  a  vacuum  press.  If  the  material  be  recrystallized  more  than  once 
the  mother  liquor  from  the  second  recrystallization  is  used  for  dissolving  up 
a  further  quantity  of  crude  substance,  and  so  on.  The  last  mother  liquors 
are  concentrated  in  a  still  and  give  on  cooling  some  trinitro-toluene  of  inferior 
quality,  and  on  further  concentration  a  still  more  impure  material  is  obtained, 
which  may  be  liquid  at  the  ordinary  temperature,  and  may  then  be  used  for 
making  plastic  explosives. 

Trinitro-toluene  may  also  be  purified  by  recrystallization  from  sulphuric 
acid.  This  method  is  used  in  France  for  the  preparation  of  material  for  the 
manufacture  of  mining  explosives.  After  this  recrystallization  it  is  washed 
methodically  with  warm  water,  neutralized  with  a  dilute  solution  of  sodium 
carbonate  and  then  rinsed  with  pure  water.  The  product  obtained  has  a 
melting-point  of  77°  to  790.1  Vender  has  patented  a  process  for  recrystallizing 
it  from  strong  sulphuric  acid,  preferably  of  100  per  cent,  strength.  After 
dissolving  at  80°  to  100°  the  acid  is  cooled  and  may  be  diluted.  It  is  claimed 
that  this  process  gives  a  large  yield  of  material  of  good  quality.2 

Another  proposal  is  to  use  nitro-toluene  as  a  solvent.3  The  trinitro- 
toluene is  heated  with  a  third  of  its  weight  of  nitro-toluene,  allowed  to  cool, 
filtered  off  and  washed  with  alcohol  to  remove  the  nitro-toluene.  The  nitro- 
toluene  containing  the  impurities  is  used  for  the  manufacture  of  a  further 
quantity  of  trinitro-toluene.  The  objection  to  this  process  is  that  the 
nitro-toluene  must  be  nearly  as  difficult  to  eliminate  as  the  natural 
impurities. 

Liquid  trinitro-toluenes  are  naturally  very  variable  in  composition,  an 
average  sample  may  contain  80  per  cent,  trinitro-toluene,  consisting  of  the 
2:4:  6-compound  with  one  or  more  other  isomers,  together  with  several 
dinitro-toluenes  and  only  a  very  small  quantity  of  mono-nitro-toluene.4 
Other  substances  are  probably  also  present.  Nobel  and  Co.  of  Hamburg 
have  patented  a  method  for  increasing  the  degree  of  nitration  of  this  product 

1  Vermin  et  Chesneau,  p.  2(51. 

2  V.  Vender,  Eng.  Pat,   18,281  of  1909,  Germ.  Pat,  237,738. 

3  Germ.  Pat.  Announcement  8729,   12  o,  Aug.  28,   1913. 

4  See  8th  Intern.  Cong.  Appl.  Chem.,   1912,  vol.  27,  p.  44. 


U.,4 


EXPLOSIVES 


without  causing  it  t<>  solidify  at  the  ordinary  temperature.1     For  this  pur- 

they  use  an  acid  rich  in  sulphuric  acid  and  poor  in  nitric.     The  following 

example  i>  given  :    1"<i  kg.  <.f  a  residue  from  purification,  containing  aboul 

15  per  cent,  nitrogen,  are  heated  for  a  long  time  at  a  temperature  of  85    t<> 

1»">    <  .  with  185  kLr.  «»f  mixed  acid  <<>ntainin;_r  B5  per  cent.  H  >< ) .  and  1")  per 

cent.  HXn;.     The  resulting  product   was   s7  kg.  of  liquid  trinitro-toluene 

aolidfying  at  14  .  containing  16-6  to  17  2  per  cent,  nitrogen  and  giving  a  Trauzl 

■f  250  t     _"         ..  whereas  dinitro-toluene  contain-  15-4  per  cent,  oitro- 

and   trinitro-toluene    18*5  per   cent,   and   gives  a  Trauzl   test   of  about 

c.c. 

Light  ha-  been  thrown  upon  the  Low  melting-points  of  tin-.-  products 
by  M.  Giua,  who  has  determined  the  melting-point  curves  of  various  binary 
mixtures  of  nitro-toluenes.2  In  each  case  examined  he  found  that  a  complex 
compound  i>  formed  having  a  melting-point  about  30*  lower  than  that  of 
either  constituent.  These  compounds  only  exist  in  the  solid  state,  when 
melted  they  dissociate  entirely.  Mixtures  containing  three  or  more  con- 
stituent- would  show  a  still  greater  depression  of  the  melting-point. 

There  are  six  possible  trinitro-toluenes.  and  according  to  M.  Copisarow  3 
they  are  all  known  and  have  the  following  melting-point-  : 


CH3 

(  H 

i 

CH 

i 

CH3 

CH3 

CH3 

no/Nno, 

^ 

NO, 

^ 

NO 

_ 

^ 

^ 

X02    NO, 

,N02 

J 

\/ 

NO, 

" '-  J 

xo2 

J 

NO 

2    N02x/ 

-x". 

Jxo, 

NO, 

NO, 

NO, 

NO 

a 

02 

y2 

6 

e3 

tt 

2  4  6 

2:3:4 

2  4  E 

3:4:5 

2  :;  5 

Melting-point 

81 

112 

104 

i 

Coloration  with 

acetane  and 

ammonia 

deep 

greeni.-h 

blue 

oran_ 

— 

red 

yellow 

red 

red 

A-  already  stated,  commercial  dinitro-toluene  consists  almost  entirely  of  the 
2  :  4-comj.ound.  and  this  on  further  nitration  gives  only  2  :  4  :  6-trin  taro- 
toluene.  which  consequently  constitutes  the  bulk  of  crude  commercial  trotyl. 
It  contains,  however,  small  quantities  of  2  :  3  :  4-  and  2:4:  .".-trinitro-toluene. 
these  being  formed  from  the  products  of  meta-nitro-toluene.*-s  2:5-dinitro- 
tolm  b  -  "•  -'  I  5-compound  and  2:3-  the  2  :  3 : 4-oompound,  3:4- 
a  mixture  of  about  7.".  pel  cent.  2:4:  ."»-  and  2.".  percent.  2  :  :;  :  4-.  It  i-  doubt- 
ful whether  3  :  .".-dinitro-toluene  i-  amongst    the  products  «»f  nitration,  but 


L914, 


1  Germ.  Pat.  264,503  of  Sept.   14.   1910. 

3  l^»  -  \V.  Will.  Ber.,   1914,  p.  7"7. 

5  \V.  Komerai  ardini.  AttiR.  Acoad  Lineei,  I'M.".,  i.,  p.  888 


1718. 


MTRO-DERIVATIVES   OF   AROMATIC   HYDROCARBONS      265 

it  can  be  prepared  indirectly;  Will  found,  however,  that  it  could  not  be  further 
nitrated  to  a  trinitro-toluene  :  it  either  remained  unchanged  or  was  oxidized 
to  dinitro-benzoic  acid.  Only  the  first  three  of  the  above  six  trinitro- 
toluenes are  therefore  known  to  be  formed  by  the  nitration  of  toluene, 
and  of  these  the  first  is  by  far  the  most  important.  It  has  not  hitherto  been 
found  possible  to  make  tetra-nitro-toluene. 

Trinitro-toluene  was  made  in  the  laboratory  by  Hepp  as  long  ago  as  1880, } 
and  in  1891  C.  Haussermann  together  with  the  Griesheim  Chemical  Factory 
took  up  its  manufacture.2  Experiments  were  carried  out  with  it  by  the 
German  military  authorities  in  the  late  'eighties,  and  early  'nineties,  and  in 
1902  they  adopted  it  for  filling  shell  and  other  purposes.  In  1901  the  manu- 
facture was  taken  up  by  the  Carbonite  Co.,  and  other  explosive  firms  soon 
followed.  Other  countries  soon  followed  suit,  Italy  in  1907,  and  Russia  shortly 
after. 

It  has  been  given  many  names,  mostly  abbreviations  of  its  scientific 
one.  In  the  English  service  it  was  formerly  known  as  T.N.T.,  but  now 
as  trotyl;  in  Italy  it  is  called  tritolo.  Other  names  are  trinol  and 
trilite. 

It  has  largely  displaced  picric  acid  for  filling  high-explosive  shell  because, 
although  it  is  not  quite  so  powerful  or  violent,  it  has  a  lower  melting-point, 
is  not  so  sensitive  and  does  not  tend  to  form  dangerous  metallic  salts.  It 
has  replaced  picric  acid  and  gun-cotton  for  filling  submarine  mines  and  torpedo 
war  heads  :  over  gun-cotton  it  has  the  advantage  of  greater  violence  and  a 
higher  density.  It  has  been  substituted  for  dinitro-benzene  in  blasting 
explosives  because  it  is  not  only  more  powerful  but  also  less  poisonous.  It 
is  used  in  the  manufacture  of  detonating  fuse  and  composite  detonators  and 
many  other  explosive  accessories. 

The  melting-point  of  the  pure  substance  was  at  one  time  stated  to  be 
82°,3  but  this  is  too  high.  According  to  Comey  it  is  80-5°-80-6°,4  Molinari 
and  Giua  as  80650,5  Rintoul  as  80-8°-80-85°,6  and  E.cales  as  80-6°  or 
80-70.7 

Trinitro-toluene  is  one  of  the  most  stable  explosives  ;  when  heated  it  does 
not  ignite  until  a  temperature  of  about  300°  is  reached  and  then  t  does  not 
explode.  Even  at  150°  there  is  no  perceptible  decomposition,  but  at  180° 
there  is  a  steady  though  slow  evolution  of  gas.8     On  June  11,  1910,  an  Order 

1  See  Annalen,  vol.  215,  p.   361. 

2  SeeC.  Haussermann,  Zeitech.  angew.  Chem.,  185)1,  p.  508;  J.  Sue.   Chem     I  ml     1891 
p.   1028. 

:!  Wijjirand,  Annalen,  128,  1803,  p.  178;   J.  Rudeloff,  S.S.,  1907,  p.  4. 


1  A.  M.  Comey,  J.   Ind.  Eng.  Che.,   1910,  p.   L03. 

'  Umd.  Reale  1st.  Scieme  Let..  4ti.  1913;  , 

6  J.  Soc.  Chem.  Ind..  1915,  p.  60. 

s  Verola,  /'.  >t  S.,  vol.  10,  1912,  p.  40. 


5  Rend.  Reale  1st.  Scieme  Lit..  4<i.  li)13;  S.S.,  1914,  p.  242. 

6  J.  Soc.   Chem.    1ml..    L915,   |».   60.  7   X  it  rospreng  staff  t\  pp.   20,     155,    293. 


EXPLOSIVES 

in  Council  wasiss  1  under  section  50  of  the  Explosives  Act.  1^7."..  exempting 
it  from  being  deemed  to  be  an  explosive  during  manufacture  and  storage, 
unconditionally,  and  when  conveyed  and  imported  provided  it  i>  properly 
packed. 

Nevertheless  it  must  not  be  forgotten  that  it  can  explode,  and  in  fact  it 
baa  caused  a  number  of  di-  In  1906  a  fire  at  the  Roburite  Factory 

at  Witten  led  to  the  explosion  of  the  store-room  containing  trinitro-toluene 
and  ammonium  nitrate  :  the  detonation  was  BO  violent  that  the  factory  was 
almost  entirely  <:  :.  and  forty-two  people  were  killed,  and  many  injui 

In  1908  an  explosion  occurred  at  J.  W.  Leitch  and  I  irks  at  Hndders- 

field,  whereby  five  men  were  injured.  The  accident  was  caused  by  placing 
a  pipe  containing  trinitro-toluene  in  a  boiler  fire  to  clear  the  pipe  by  malting 
out  the  contents.     In  1909  several  men  were  killed  by  an  explosion  in  the 

'allizing  house  at  Allendorffs  factory  at  Schonebeck.  a.E.  This  accident 
is  a  •mewhat  puzzling,  as  the  el:-  te  -  emed  to  be  too  great  to  be  due  only 
to  an  explosion  of  vapour,  and  yet  not  nearly  so  greal  vould  have  been 

caused  by  the  explosion  of  even  a  small  proportion  of  the  trinitro-toluene 
present  in  the  building.2  In  1012.  Ion  kLr.  exploded  from  some  unknown 
cause  in  a  cask  in  the  washing  house  of  a  German  factory,  whereby  four  men 
were  killed  and  four  severely  injured.  It  would  seem  that  the  r-ubstar. 
liable  occasionally  to  contain  some  impurity,  which  renders  it  much  more 
dangerous.  To  a  cause  of  this  sort  is  a.-eribeda  fatal  explosion  that  occurred 
in  1907  in  a  vacuum  still  from  which  mono-nitro-toluene  was  distilled.3  Dupre 
found  that  the  addition  of  a  little  caustic  potash  caused  trinitro-toluene  to 
explode  when  heated  to   160    4 

/3-and  y-trinitro-toluene  are.  however,  somewhat  le>s  stable  than  the 
a-compound.  Their  behaviour  with  alkali  was  investigated  by  W.  Will,* 
who  found  that  the  S-  and  7-compounds  when  treated  with  alkali,  even  an 
alkaline  carbonate,  whether  in  the  presence  or  absence  of  alcohol,  are  con- 
verted into  salts  of  dinitro-cresol.  and  these  have  much  the  same  properties 
This  change  even  takes  place  when  they  are  heated  with 
lead  oxide  in  the  presence  of  alcohol,  lead  cresylates  being  formed.  The 
a-  compound,  on  the  other  hand,  is  not  attacked  by  heating  with  lead 
oxide    and    alcohol,   and   by    1    per  cent,   soda   solution  at   95 :    to    1""     it 

>nly  attacked  a  third  as  rapidly  as  the  other  two.  Alkali  alone 
converts  the  a-compound  into  red  colouring  matters,  and  in  the  presence 
of   an   oxidizing   agent    gives    hexanitro-dibenzyl.    which    i<   comparatively 

•le. 

JjS      1907,   pp.  333.  413.  and  116. 
2  Set   >>..   1  '.«•;«.  p.  213.  OJSL,   1908.  p.  298. 

4  A.R..  1903;  p.  - 

5  B<r..  1914,  p.  711  ;  m  obo  M.  I  •  1  in*  .     . 


NITRO-DERIVATIVES   OF  AROMATIC  HYDROCARBONS 

CH  .  CH ., CH  , 


267 


N02r//\N02  +  alkali  and       X02, 
a   I  oxidizing  -> 

\y/  agent 

N02 
m.p.   80-6° 

CH3 


,XO„    NO, 


y\ 


V 

N02  NOg 

m.p.  212° 

CH*  CHo 


NO, 


CH 


.     |N02 

p   1  -4-  alkali  -> 

NO, 

m.p.   112° 


\xo„ 


)NO, 

y 
/'oh    NOa\y 

NO,  N02 

m.p.    101°  m.p.   104 


-j-  alkali  -> 


OH 


NO., 


Except  as  regards  the  melting-point  the  physical  properties  of  the  three  Properties, 
isomeric  trinitro-toluenes  are  similar.  They  have  about  the  same  specific 
gravity  of  about  1-62,  the  same  temperature  of  ignition,  290°  to  310°,  the  same 
heat  of  combustion  of  about  3660  Calories,  give  the  same  result  in  the  Trauzl 
test,  and  are  about  equally  sensitive  under  the  falling  weight,  although  the 
a-compound  is  slightly  less  sensitive  than  the  y. 

Trinitro-toluene,  which  has  been  melted,  has  a  density  of  1-57  to  1-60  ;  Density, 
when  powdered  and  compressed  Dautriche  found  that  it  had  the  following 
densities  : 


Pressure 

Mean  density 

kg.  /cm.2 

tons  in2 

275 

1-75 

1-320 

685 

4-35 

1-456 

1375 

8-73 

1-558 

2060 

131 

1-584 

2750 

17-5 

1-599 

3435 

21-8 

1-602 

4125 

26-2 

1-610 

whence  it  is  concluded  that  the  limiting  density  for  the  compressed  material 
is  about  1-62.1 

NITRO-XYLENES,   ETC. 

The  next  homologue  of  the  benzene  series  is  xylene,  of  which  there  are 
three  isomers,  all  of  which  are  present  in  coal  tar,  and  have  boiling-points 
close  together  between  137°  and  142°.     It  is  not  practicable  to  separate  them 

1  P.  et  S.,  vol.   16,   1912,  p.  28. 


2G8  EXPLOSIVES 

on  a  commercial  scale.  Nitro-xylene  is  a  constituent  of  some  blasting  explo- 
sives. Monachit  for  instance.1  hut  for  this  purpose  the  crude  mixture  is  used 
which  is  obtained  by  nitrating  the  mixture  of  the  three  xylenes.  As  these 
are  nitrated  with  different  degrees  of  difficulty  a  mixture  tri-,di- and  even  mono- 
nitro-xylenes  is  obtained,  and  in  const  quence  of  the  complexity  of  the  mixture 
it  is  often  liquid.  If  the  crude  xylene  contain  other  substances  as  well,  the 
nitro-producl  will,  of  course,  be  still  more  complex.  The  liquid  products 
can  be  used,  like  liquid  trinitro-toluene.  for  the  manufacture  of  plastic  explo- 
sives, the  liquid  being  thickened  hy  dissolving  some  collodion  cotton  in  it. 
Some  inventors  have  proposed  to  nitrate  wide  fractions  of  coal  tar  naphtha. 
ThusC.  Distler,  E.  Blecher  and  C.  Lopez  2  nitrate  the  fraction  boiling  between 
130°  and  170°,  and  O.  Silherrad  3  that  between  200°  and  350°.  There  is  no 
published  information  as  to  the  chemical  stability  of  these  complex  mixtures 
of  nitrocompounds. 

NITRO-NAPHTHALENES 

This  substance  is  made  by  nitrating  naphthalene  with  a  mixed  acid  con- 
taining only  slightly  more  than  the  theoretical  amount  of  nitric  acid.  The 
acid  is  placed  in  a  nitration  pot  provided  with  a  stirrer  and  the  naphthalene 
added  a  little  at  a  time,  the  temperature  being  kept  below  40°.  Then  the 
liquid  mixture  is  heated  to  G0°  for  an  hour.  A  considerable  amount  of  red 
funics  is  evolved  in  consequence  of  secondary  reactions  involving  the  forma- 
tion of  phthalic  acid  and  other  oxidation  products.  On  cooling  the  nitro- 
naphl  halene  crystallizes  out  on  the  surface  of  the  acid,  which  is  then  run  off. 
The  product  is  centrifuged,  washed  with  water  and  dilute  sodium  carbonate 
solution,  then  with  water  again  and  dried  at  50°.  It  may  be  purified  by 
recrystallization  from  alcohol  or  benzol.  The  yield  is  about  IK)  per  cent., 
whereas  theoretically  it   should  be   135  per  cent. 

There  are  two  mono-nitro-naphthalenes,  but  under  ordinary  conditions 
of  nitration  the  <<-compound  only  is  formed.  The  melting-point  of  this  is 
given  variously  as  58-5c  and  61°,  but  the  commercial  product,  not  being  quite 
pure,  melts  at  about  55°.  It  is  a  neutral  body,  insoluble  in  water,  hut  soluble 
in  ether,  alcohol,  carbon  bisulphide,  petroleum  ether,  etc.  As  an  explosive 
it-  power  is  small,  but  it  is  used  in  cheddite  as  a  combustible  and  agglonui  ant . 
its  softness  helping  to  bind  the  powder  together.  Its  sp<  cific  gravity  is  1  -331 
at  4°. 

No, 


1  See  8JS.,   1909,  p.   inc.. 

2  Germ.  Pats.  212,906, 214,887, 242,731  ;  French  Pat.  380,996;  Eng.  Pat.  l9,565of  L907 

3  Eng.  1'iits.   13,860,    13,861   and    19,381  of  L912. 


NITRO-DERIVATIVES   OF   AROMATIC   HYDROCARBONS      269 

If  nitro-naphthalene  be  further  nitrated  in  the  same  way  a  mixture  of  two  Dinitro- 
dinitro-naphthalenes  is  obtained:  c  Ph  n^o1 

NO.,  NO,  NO, 


N02 

a  or  1:5 

(3  or  1:8 

in.]..   217° 

in.p.   170c 

or  naphthalene  may  be  nitrated  directly  to  the  dinitro-compound  if  a  sufficient 
quantity  of  acids  of  suitable  strength  be  used.  The  commercial  product 
melts  at  about  140°.  Both  isomers  are  used  for  the  manufacture  of  dye-stuffs. 
To  separate  them  advantage  is  taken  of  the  fact  that  the  a-compound  is  almost 
insoluble  in  many  organic  solvents,  which  dissolve  the  /3-compound  with  ease. 
The  crude  product  is  washed  with  water,  treated  with  carbon  bisulphide  to 
remove  nitro-naphthalene,  and  then  with  acetone  to  dissolve  /3-dinitro-naph- 
thalene.  But  for  the  manufacture  of  explosives  it  is  not  necessary  to  separate 
the  isomers.  Dinitro-naphthalene  is  a  constituent  of  Grisounites  made  in 
France,  of  Ammonite  and  some  other  similar  explosives.  It  is  decidedly 
insensitive  and  not  at  all  powerful  as  an  explosive. 

This  is  made  by  nitrating  mono-  or  di-mtro-naphthalene  with  moderately  Trinitro- 
strong  mixed  acid.  A  mixture  of  several  isomers  is  obtained  melting  at  about  ci0h5n3o, 
110°.  This  is  washed,  and  heated  in  copper  crucibles  to  a  temperature  above 
the  melting-point  until  no  more  gas  is  evolved.  The  molten  mass  is  then 
poured  into  water,  powdered,  centrifuged  and  dried.  It  is  used  in  the  same 
classes  of  explosives  as  dinitro-naphthalene,  and  has  also  been  added  to 
smokeless  powders  as  a  stabilizer.1 

This  is  made  by  nitrating  dinitro-naphthalene  with  a  mixture  of  nitric  Tetranitro- 
acid  and  oleum.  It  is  a  mixture  of  several  isomers  and  melts  at  about  220°.  Cjuh4n4o, 
It  has  been  but  little  used  in  explosives,  probably  because  the  yield  is  small. 

M.  Patart  has  in  the  laboratory  nitrated  naphthalene  with  a  large  numb<  r 
of  different  acid  mixtures,  using  the  acid  in  the  proportion  of  30  pails  to  1  of 
naphthalene.2  The  results  have  been  plotted  by  Saposhnikoff  on  a  triangular 
diagram  similar  to  that  on  p.  138.3  The  curves  showing  the  degree  of  nitration 
attained  take  a  very  similar  course  to  those  for  nitro-cotton.  In  practical 
manufacture  the  proportion  of  acid  used  is  very  much  smaller  than  Patart 
employed,  but  the  results  may  be  of  value  as  indicating  the  composition  that 
the  waste  acids  should  have. 

1  Vennin  et  Clicsncau,  p.  268. 

2  P.  ct  S.,  vol.  be.,   p.   38  ;    vol.   xi.,  p.    147. 

3  J.  Russ.,  Phya.  Clan,.  SOC.,  1!»14,  p.  1102  ;   Chan.  Soc,  Abstr.,  1915,  i.,  p.  393. 


270  EXPLOSIVES 

POISONING  BY  AROMATIC  COMPOUNDS 

The  aromatic  hydrocarbons  have  a  decided  toxic  action ;  the  vapours  of 

benzene  and  toluene  produce  giddiness  and  finally  insensibility  when  inhaled. 

kera  who  are  constantly  ex]  to  the  fumes  may  suffer  severely  in 

health.     Adequate   fans   should   therefore   be  provided  when   these   volatile 

liquids  are  «.  in  open 

The  nitro-derivatives  of  these  hydrocarbons  are  more  poisonous  than 
they  are  themselves,  but  are  not  so  volatile.  Dinitro-benzene  and  dinitro- 
toluene  are  specially  poisonous,  and  their  use  in  explosives  is  therefore 
objectionable.  Explosives  containing  them  should  not  be  handled  with  the 
bare  hands,  and  during  all  manufacturing  operations  precaution  must  be 
taken  to  prevent  workers  inhaling  the  dust  and  fumes.1  A  French  Commi- 
which  reported  on  this  subject  in  1012  ■  found  that  : 

1 .  The  workers  most  frequently  affected  are  generally  young  people  who 
have  not  been  working  long  in  the  factory. 

2.  Most  of  these  workers  are  drinkers. 

Serious  attacks  are  most  frequent  in  July  and  August.,  and  especially 
when  the  weather  is  thundery,  the  vapours  being  liberated  to  a  greater  extent 
the  higher  the  temperature. 

The  symptoms  are  drowsiness,  sometimes  going  as  far  as  unconsciou- 
g    stric  troubles,  excema.  and  frontal  headache.     In  mild  cases  a  few  hours 
in  the  open  air  may  cure  the  patient.     Severe  cases  may  end  in  death.    Workers 
who  si  -       "f  being  affected  should  at  once  be  transferred  toother  work 

at  any  rate  for  a  time. 

Trinitro-benzene  and  -toluene  are  generally  considered  to  be  much  less, 

-  nous  than  the  dinitro-compounds.  There  have,  however,  been  some 
cases  of  fatal  poisoning  by  trotyl,  but  these  may  have  been  due  really  to 
the  presence  of  dinitro-toluene. 

Picric  acid  has  a  disagreeable  bitter  taste,  but  is  not  very  poisonous.     The 

chlor-nitro-compounds.  on  the  other  hand,  are  more  dangerous  than  those 

not   containing   chlorine.      Some   of    the   other    nitro-derivatives.    such    as 

tetryl   and    hexa-nitro-diphenylamine,    have    been    found    to    be    decidedly 

- 

The  curative  measures  adopted  in  Germany  are  :  immediate  removal 
from  the  factory",  artificial  respiration  and  inhalation  of  oxygen,  and  non- 
alcoholic stimulants.  As  preventative  measures  alcohol  is  forbidden  during 
working  hours,  and  only  moderate  quantities  are  allowed  at  other  times.  The 
work-  s  s  ;ld  wear  leather  gloves,  and  clothes  fitting  tightly  at  the  neck, 
wrists  and  ankles.     Their  boots  should  have  wooden  soles,  and  they  should 

the  Home  Secretary  by  Dupre  and  Smith,   1893, 
2  P.  a  &,  vol.  xvi.,  p.   144. 


NITRO-DERIVATIVES   OF    AROMATIC    HYDROCARBONS     271 

put  cotton  wool  in  their  ears,  and  when  necessary  they  should  wear  respirators. 
Meals  must  not  be  taken  in  the  working  rooms,  and  before  eating  the  worker 
must  wash  his  face  and  hands  with  soap  and  water  and  clean  his  nails  with  a 
nail-brush,  and  rinse  his  mouth  out  with  a  2  per  cent,  solution  of  tincture  of 
myrrh.     The  workers  have  daily  a  douche  bath  and  once  a  week  a  tub.1 

1  R.  Escales,  Nitrosprengatoffe,  p.  211  ;    see  also  S.S.,  1908,  p.  259. 


CHAPTER  XX 

OTHER  NITRO- AROMATIC  COMPOUNDS 

I  )>n\  ,ii  i\  88  of  Aniline 

Aniline  •  ,,H5XH2  :  Diphenylamine  (CGH5),XH  :  Hexanitro-diphenylamine 
(( '6H2X306)2XH  :  Nitro-anilinee  :  Nitro-methylanilines  :  Manufacture  of  tetryl  : 
Properties  <>f  tetryl  :  Higlier  nitro-derivativea  of  methyl-aniline  :  Picric  acid, 
C6H;,X307  :  Properties  :  Higher  nitro-phenols  :  Styphnic  acid  ('GH3X~303 
Trinitro-cresol,  C6H.OH,CH3(X02)3  :  Picrates  and  trinitro-cresylates  : 
Trinitro-anisole,  C6H2OCH3(X02)3 :  Kinetics  of  nitration 

Aniline  is  made  from  nitrobenzene-  by  treating  it  -with  iron  borings  and 
hydrochloric  acid.  The  nascent  hydrogen  replaces  the  oxygen.  When 
reduction  is  complete  the  aniline  is  distilled  in  a  current  of  steam,  allowed 
bo  Bettle,  and  purified  by  distillation  in  vacuo.  For  details  of  the  processes 
see  Thorpe's  Dictionary  of  Applied  Chemistry,  vol.  i,  p.  260. 

XO,  XH, 


Aniline,  when  pure,  is  a  colourless  liquid  with  a  specific  gravity  of  P025  at 
15°/15°  and  boiling  at  184°.  It  is  used  very  extensively  for  the  manufacture 
of  synthetic  dyes,  and  some  of  its  derivatives  are  used  in  the  explosives  industry. 
The  substance  itself  has  been  used  as  a  stabilizer  in  smokeless  powders,  but 
its  strongly  basic  character  and  its  volatility  are  serious  objections  :  it  has 
now  been  replaced  for  this  purpose  by  other  substances,  notably  diphenylamine. 
This  is  made  by  heating  aniline  and  aniline  hydrochloride  together  in 
an  autoclave  for  thirty  to  thirty-five  hours  at  220°  to  230°.  The  product 
i-  extracted  with  hot  dilute  hydrochloric  acid,  which  dissolves  the  un- 
changed aniline  hydrochloride  whilsl  the  diphenylamine  Moats  on  the  surface 
as    free  base.     The   yield  is  60  to  70  per  cent,  of  the  aniline  used.     It  is  a 


272 


OTHER  NITRO-AROMATIC   COMPOUNDS  273 

crystalline  solid  melting  at  54°  and  boiling  at  310°.  It  is  almost  insoluble 
in  water,  soluble  in  alcohol,  benzene  and  ether,  and  only  feebly  basic.  It  is 
used  as  a  stablizer  in  military  smokeless  powders,  and  also  for  the  manufacture 
of  dyes. 

One  of  these  dj^es  is  the  hexanitro-derivative,   known  as   "  Aurantia,"  Hexanitro- 
which  is  made  either  by  nitrating  diphenylamine  or  by  other  synthetic  methods.1  amine*/1" 
It  is  a  powerful  explosive, but  does  not  appear  to  be  used  much  for  this  purpose,  (C,h2n30o 
nor  is  it  any  longer  used  much  as  a  dye.     It  is  acid  in  character  and  somewhat 
poisonous.     Its  colour  is  lemon  yellow,  and  it  melts  at  238°.     It  is  more  sensi- 
tive to  blows  than  tetryl.2 

NO,  NO, 


N°2\        /  ~  NH  ~~  X         /N°2 
N02  NO, 

The  direct  nitration  of  aniline  is  liable  to  give  low  yields,  because  by-reactions  Nitro- 
set  in.  Therefore  it  is  often  combined  first  with  acetic  acid  to  form  acetanilide,  amlmes' 
which  is  nitrated  and  then  heated  with  dilute  acid  or  alkali  to  remove  the 
acetyl  group.  In  this  wayortho-  and  para-nitro- aniline  can  be  made.3  The 
meta-compoun  '  is  obtained  by  the  partial  reduction  of  meta-dinitro-benzene. 
Various  other  indirect  methods  can  be  used.  The  mono-  and  di-nitro-anilines 
are  readily  nitrated  further.  Thus  ortho-nitroaniline  gives  2:4:  6-trinitro- 
aniline,  or  picramide,  which,  however,  is  more  easily  made  by  the  action 
of  ammonia  on  trinitro-chlor-benzene.  This  is  a  powerful  explosive,  but  has 
not  been  used  on  a  large  scale. 

Similarly  meta-nitro- aniline  gives  tetra-nitro-aniline,4  and  Flurscheim  has 
proposed  to  use  this  as  a  commercial  explosive  5  as  it  is  more  powerful  than 
any  substance  at  present  in  use.  He  makes  the  nitro- aniline  by  treating 
commercial  di nitro- benzene  with  sodium  bisulphide  and  water.  The  product 
thus  obtained,  without  previous  jmrification,  is  nitrated  with  mixed  acid  at 
about  70°  or  lower.  The  nitration  proceeds  rapidly.  The  crystals  of  tetra- 
nitro-aniline  are  filtered  off  from  the  undiluted  waste  acids,  washed  with 
water  and  dried.  In  this  way  commercial  dinitro-benzene  yields  almost  its 
own  weight  of  pure  tetra-nitro-aniline,  whereas  theoretically  it  should  yield 
1*53  times  its  weight.  Tetra-nitro-aniline  is  a  yellow  solid  with  a  specific 
gravity  of   1-867.     It  cannot  be  melted  without  decomposition  ;    if  heated 

1  See  S.S.,   1910,  p.   16  ;    also  T.  Carter,  S.S.,   1913,  p.  205. 

2  F.  Langenscheidt,  S.S.,  1912,  p.  446. 

3  For  the  proportions  and  yields  see  A.  F.  Holleman,  J.  C.  Hartog  and  T.  v.  d.  Linden, 
Ber.,   1911,  p.  704. 

*  B.  Flurscheim  and  T.  Simon,  Proc.  Chem.  Soc,  1910,  p.  81. 

5  Eighth  Intern.  Cong.  Appl.  Chem.,  1912,  vol.  iv.,  p.  31  ;  S.S.,  1913,  p.  185.  Eng. 
Pats.  3224  and  3907  of  1910;    Germ.  Pats.  242,079  and  241,697. 

VOL.  I.  18 


274 


EXPLOSIVES 


Nitro- 

methyl- 

aailines. 


Manufacture 
of  tetryl. 


minute  it  melts  at  about  210°.     It  is  claimed  for  it  that  it  is  not  more 
fltive  than  tetryl,  and  that  it  i>  stable,  but  on  boiling  with  water  it  is 
converted  into   tiinitro-amino-phenol,  and   the  nee  ifl  obtained 

instantaneously  at  the  ordinary  temperature  by  the  action  of  an  eqii' 
solution  of  sodium  acetate. 

NH- 
NO,r]NO, 

NO, 

Methyl-aniline  is  made  by  heating  anline  hydrochloride  or  sulphate  with 
methyl  alcohol.  On  nitration  four  NO,  groups  can  be  made  to  enter  the 
molecule  without  any  great  difficulty,  three  combining  with  the  carbon  atoms 
of  the  benzene  ring  and  one  with  the  nitrogen.  This  substance  i-  often  caLled 
tetraintro-aiiiline.  but  strictly  speaking  its  scientific  name  is  trinitro-phenyl- 
nitramine  :  commercially  it  is  called  tetryl  or  tetralite.  It  was  first  described 
by  Romburgh  in  1883, J  and  is  obtained  also  on  nitrating  dimethyl-aniline, 
which  is  made  in  a  similar  manner  to  methyl-aniline. 

CH3       XO, 

\  / 
N 


NH 

j 

NO 

/\ 

OH 

NO 

m.p. 

174 

-17.:, 

NO 


NO 


NO; 

The  following  is  the  method  of  manufacture  scribed  by  F.  Langen- 

tdt  :  -    The  dimethyl-aniline  used  should  be  of  a  high  degree  of  purity  ; 
95  per  cent,  of  it  should  distil  over  within  a  range  of  lc  or  14/  <  .     Its  specific 
it]  ifl  0-9567  ;r  23  ,  and  it-  boiling-point  190*     I  7<  0  mm.  :     According  to 
the  Tables  of  Landolt-Born-tein,  1912,  the  specific  gravity  is  t  2<»:  4: 

and  the  boiling-point  193-1°  at  760  mm.)     The  nitration  vesfi  f  an 

enamelled  pot  provided  with  an  enamelled  stirrer,  and  a  jacket  through  which 
water  or  steam  can  be  passed.  In  it  l"""  kg.  of  colourless  lead-free  Eradphmic 
acid  <>f  '.'7  to  98  per  cent,  strength  are  placed,  the  stirrer  is  started  and  100  kg. 
of  the  d'methyl-aniline  is  slowly  run  in  :  thi-  takes  about  two  hours.  The 
acid  in  dissolving  the  dimethyl-aniline  becomes  coloured  light  brown,  but 
the  colour  must  not  be  so  dark  that  one  cannot  see  through  a  layer  5  cm. 
thick.     A  dark  colour  is  generally  due  to  insufficient  cooling  or  too  rapid 

1  R(c.  trav.  chim.,  vol.  ii.,  p.   108. 

-    5   -■•  191%  p.  44"        5  :     M.  Yasquez,  &&,  1911.  p.       - 


OTHER  XITRO-AROMATIC  COMPOUNDS  275 

addition  of  the  dimethyl-aniline.  The  sulphuric  acid  solution  should  be 
nitrated  without  unnecessary  loss  of  time,  otherwise  there  may  be  darkening, 
and  the  dark  colour  cannot  be  removed  from  the  finished  tetrvl. 

The  nitration  is  carried  out  in  the  same  or  a  similar  vessel.  In  it  are  placed 
first  430  kg.  of  nitric  acid  of  47°  B.  (sp.  gr.  1-483,  87-3  per  cent.  HX03)  and 
heated  to  40°  C  and  the  sulphuric  acid  solution  is  run  in  in  a  thin  stream. 
At  first  the  temperature  must  not  be  allowed  to  rise  above  44°,  but  when 
two-thirds  have  been  run  in  the  temperature  may  be  allowed  to  rise  to  55°. 
The  addition  takes  eight  or  nine  hours  :  after  it  is  finished  the  temperature 
is  maintained  for  another  two  hours  at  53°  to  55°  to  complete  the  nitration. 
The  oxidation  of  one  of  the  CH3  groups  causes  the  contents  of  the  vessel  to 
froth  considerably.  When  the  nitration  is  complete  the  mixture  is  cooled 
to  the  ordinary  temperature  and  allowed  to  stand  over  night.  The  tetranitro- 
methyl-aniline  separates  out  on  the  surface  in  tine  crystals,  provided  that 
the  nitric  acid  used  is  not  stronger  than  as  stated  above.  If  stronger  acid 
be  used  the  crystals  are  larger  and  cannot  be  washed  properly.  Next  morning 
the  waste  acid  is  run  off  ;   it  has  about  the  following  composition  : 

Sulphuric     cid.  .....      7404 

Nitric  acid        .  .  .  .  .  .11-05 

Nitrogen  peroxide      .....        2-58 

Nitro -bodies      .  .  .  .  .  .0-24 

Water  (by  difference)         .  .  .  .12-19 


100 
Specific  gravity         .  .  .  .  .       1.75 

After  draining  off  the  waste  acid  the  solid  product  is  washed  by  means  of 
dilute  sulphuric  acid  on  to  the  plate  of  a  vacuum  filter,  where  it  is  washed 
with  more  dilute  sulphuric  acid.  Then  it  is  removed  to  another  filter,  where 
it  is  washed  with  water  until  it  is  neutral.  To  test  for  this  15  or  20  g.  of  the 
wet  substance,  equivalent  to  about  10  g.  dry,  are  boiled  with  50  c.c.  water, 
cooled,  filtered  and  washed  :  the  filtrate  should  not  require  more  than  0-2  c.c! 
N/10  caustic  soda  solution  to  render  it  neutral  to  phenol  phthalein.  This 
amount  is  principally  due  to  the  faint  acid  character  of  the  pure  tetrvl.  The 
substance  is  then  dried.  It  now  has  a  melting-point  of  126D  to  127°,' and  the 
yield  is  about  210  kg.,  whereas  according  to  theory  there  should  be  237  kg. 
from  100  kg.  of  dimethyl-aniline. 

It  is  necessary  further  to  purify  the  tetrvl  by  recrystallization.  as  small 
amounts  of  impurity  seriously  affect  its  stability.  For  this  purpose  500  kg. 
are  dissolved  by  boiling  in  1850  kg.  of  pure  benzene  and  allowed  to  crystallize 
out,  fiftered  off  and  dried.  The  benzene  is  recovered  from  the  mother  liquor 
by  distillation,  but  some  water  is  added  to  the  still  to  prevent  heating  the 
solid  residue  above  100°.     About  13  per  cent,  of  the  crude  tetrvl  is  lost  by 


276 


EXPLOSIVES 


this  process  and  remains  in  the  still.     As  this  residue  i^  unstable  it  i-  destroyed 
by  burning.     There  are  also  other  methods  of  purification  in  use. 

Pure  tetryl  looks  like  flour  \\ i t h  a  faint  yellow  colour.  The  melting-point 
of  the  pure  substance  is  129°  to  130°,  that  of  a  good  commercial  material 
127-.-)    to   L28-2  . 

Tetryl  is  a  more  powerful  explosive  than  trotyl  or  picric  acid,  but  it  is 
also  somewhat  more  sensitive,  without,  however,  being  dangerously  BO  with 
ordinary  precautions.  This  makes  it  very  suitable  for  use  as  an  intermediate 
detonating  agent.  It  is  used  in  conjunction  with  fulminate  as  a  filling  for 
detonators,  ami  as  a  primer  for  high  explosive  shell.  Detonating  fuse  has 
also  been  tilled  with  it.  According  to  Langenscheidt  it  gives  a  Trauzl  tesl 
of  400  to  480  c.c.,  and  in  the  falling  weight  test  it  requires  a  weight  of  5  kg. 
falling  30  to  40  cm.  to  explode  it.  It  is  somewhat  poisonous,  and  should 
not  be  handled  more  than  is  necessary  as  it  is  liable  to  set  up  skin  irritation. 
It  is  a  component  of  some  ammonium  nitrate  explosives  such  as  Fortex, 
but  its  comparative'}-  high  cost  of  manufacture  prevents  its  extensive  use 
for  this  purpose. 

Still  higher  nitro-derivatives  of  methyl-aniline  have  been  prepared,  but 
arc  unstable.  Tetranitro-phenyl-methyl-nitramine  is  a  substance  melting 
at  146°  to  147  ;  on  boiling  with  water  one  of  the  nitro-groups  is  replaced 
by  <  >H  and  nitric  acid  is  formed: — 

N02 


CH3         NO, 

\/ 
N 


NO. 


\no, 


V 

NO, 


CH 


NO. 


No 


Other  reagents  produce  s'milar  changes.1 


The  corresponding  penta-nitro-derivative  is  a  yellow  crystalline  Bubstance 

which  melts  at  132°  and  explodes  at  a  higher  temperature.2 

1  Romburgh,  Rec.  trav.  chini.,  1889,  p.  108  ;    Romburgh  and  Schepers,  Proc.   K.  Afoul. 
Wetenach.,  Amsterdam,    1913,  p.  369. 

2  J.  J.  Blanksma.  Proc.  K.  A  font.  Wetensch.,  Amsterdam,  l(.t<i2.  p.  137. 


OTHER   NITRO-AROMATIC   COMPOUNDS  277 

NITRO-PHENOLS 

Phenol  (carbolic  acid)  is  nitrated  very  easily  even  by  dilute  nitric  acid 
yielding  a  mix!  ure  of  ortlio-  and  para-nitro-phenol,  and  these  on  further  nitration 
give  2  :  4-dinitro-phenol,  which  may  also  be  obtained  by  the  direct  nitration 
of  phenol  with  mixed  acid.  These  compounds  are  not,  however,  used  as 
explosives,  although  they  can  be  detonated  with  some  difficulty. 

Picric  acid,  or  2  :  4  :  6-trinitro-phenol,  has,  however,  been  used  on  a  very  Picric  acid 

CeH,N307. 

XO.,f    INO, 


N02 

large  scale  as  a  military  explosive,  and  is  still,  in  spite  of  the  fact  that  trotyl 
is  generally  preferred. 

This  substance  is  the  final  product  of  the  action  of  nitric  acid  on  a  large 
number  of  substances  containing  a  benzene  nucleus,  just  as  oxalic  acid  is  the 
result  of  the  oxidation  of  many  bodies  of  the  fatty  series.  Picric  acid  is 
obtainable  from  indigo,  aloes,  gum-resins,  wool,  silk,  etc.,  but  the  common 
idea  that  the  yellow  colour  produced  by  nitric  acid  on  animal  tissues,  such 
as  skin,  wool,  etc.,  is  due  to  the  production  of  picric  acid  is  erroneous  :  it  is 
due  to  the  formation  of  xanthoproteic  acid. 

Picric  acid  was  formerly  prepared  by  the  direct  action  of  nitric  acid  on 
phenol,  but  is  now  made  by  first  dissolving  the  phenol  in  strong  sulphuric 
acid  and  then  acting  on  the  resulting  phenol-sulphonic  acid  with  excess  of 
nitric  acid.  Mono-  and  dinitro-phenol  may  result  if  the  action  is  not  carried 
far  enough.  Picric  acid  separates  from  the  acid  mixture  as  an  oily  liquid, 
which  solidifies  on  cooling. 

A.  H.  Ney  in  a  lecture  delivered  before  the  National  Exhibition  of  American 
Chemical  Industries  in  New  York  has  given  the  following  information  about 
the  manufacture  of  picric  acid  :  * 

The  technical  production  of  picric  acid  is  to-day  carried  out  by  two  cb'stinct 
processes  : 

1.  The  first  and  older  method,  which  even  to-day  is  employed  almost 
exclusively,  consists  in  treating  phenol  with  concentrated  sulphuric  acid  ,it 
about  100°  to  110°  until  the  odour  of  phenol  has  disappeared  and  the  reaction 
product  is  completely  soluble  in  water,  and  nitrating  the  sulphuric  acid  thus 
obtained  with  an  excess  of  nitric  acid,  preferably  in  the  presence  of  an  excess 
of  sulphuric  acid. 

1  J.  Met.  an, I  Chem.  Eng.,  1915,  p.  686;  Chem.  Trade  Jour.,  1915,  p.  385.  See  also 
S.S.,  1910.  P.    I.-.. 


27s  EXPLOSIVES 

2.  The  second  and  more  modern  method  employs  as  starting  material 
chlorbenzol,  which  is  dinitrated  to  dinitro-chlorbenzene  ;  this  product  is 
Beparated  from  the  spent  oitrating  mixture,  the  chlorine  atom  replaced  by 
hydroxy]  by    heating  with   caustic  soda,  and  the   resulting   dinitro-phenol  is 

nitrated. 

The  possibility  of  a  third  commercial  method  for  the  production  of  picric 
acid  is  suggested  by  an  old  publication  by  Eepp/who  claims  to  have  obtained, 

with  an  excellent  yield,  picric  acid  by  oxidizing  trinitro-benzene  in  alkaline 
solution  with  potassium  ferric  cyanide,  the  use  of  other  mi'd  oxidizing  agents 
being  also  suggested. 

In  view  of  the  difficulty  in  obtaining  trinitro-benzene  with  anything  like 
a  satisfactory  yield,  the  commercial  feasibility  of  such  procedure  is  open  to 
grave  doubt,  although  the  writer  has  private  information  that  a  small  plant 
is  at  the  present  time  producing  picric  acid  to  some  extent  by  a  process  pur- 
porting to  be  based  upon  this  method. 

The  chemical  and  technical  literature  contains  many  suggestions  and 
several  descriptions  for  the  manufacture  of  picric  acid,  all  of  them,  however, 
being  obsolete.  Chemically,  the  preparation  of  pictic  acid  is  very  simple 
and  easy,  and,  as  a  matter  of  fact,  it  would  seem  almost  impossible  for  any  one 
pla.ing  phenol  and  nitric  aeid  together,  in  some  form  and  manner,  not  to 
obtain  picric  acid.  Technically,  however,  the  manufacture  involves  several 
difficull  problems,  mainly  due  to  the  fact  that  the  handling  of  unmixed  nitric- 
acid  is  a  difficult  and  dangerous  operation  excluding  the  use  of  materials  for 
receptacles,  etc.,  usually  employed  in  the  chemical  industry,  and  the  someAvhat 
exaggerated  fear  of  contamination  by  inorganic  salts,  detrimental  to  the 
-lability  of  the  product.  The  drying  and  pulverizing  of  the  material  is  a 
very  dangerous  operation,  which,  however,  is  now  seldom  required  in  chemical 
fact. .lie-,  the  Ordnance  works  usually  requiring  delivery  of  the  wet  crystals 
with  a  moisture  content  of  approximately  20  per  cent. 

The  manufacture  of  picric  acid  is  carried  out  as  follows  : 

A  large  sulphonation  kettle  of  the-  usual  construction,  preferably  lead- 
lined,  with  steam  jacket,  bottom  discharge  and  agitator,  i-  charged  with 
one  part  phenol  and  four  parts  sulphuric  acid.  '.•*  per  cent.  The  mixture  is 
heated  under  agitation  until  a  sample  appear-  completely  sulphonated — 
that  is.  soluble  in  water  without  turbidity,  and  having  no  odour  of  phenol. 
The  content  of  the  sulphonation  kettle  is  now  divided  into  the  nitrators, 
which  are  receptacles  suspended  in  a  space  adapted  to  have  hot  or  cold  water 

circulated  therein.  To  the  content  of  each  kettle  an  equal  part  of  sulphuric 
acid  i-  added,  and  after  reducing  the  temperature  t«»  below  20  the  nitrating 
acid  i-  run  in.  This  is  preferably  a  usual  mixture  of  equal  parts  of  sulphuric 
icid  and  nitric  acid  of  62  per  cent,  st  length,  but  other  proportions  may  be 

1  Annul,,      1882  .  215,  ]..  344. 


OTHER  XITRO-AROMATIC  COMPOUNDS  279 

used.  Instead  of  the  three  molecules  required  by  the  theory,  four  molecules 
of  HX03  are  added:  the  temperature  is  kept  below  4u  while  the  first  30 
to  40  per  cent,  nitric  arid  is  run  in.  and  then  gradually  increased  to  70°  or 
80°,  hot  water  being  circulated  towards  the  end  of  the  operation  and  one  to 
two  hours  afterwards.  Proper  ventilation  must  be  provided.  Air  may  be 
blown  through  the  nitrators  before  removing  their  content  in  order  to  remove 
the  nitrous  gases  formed.  The  content  is  now  removed  into  an  acid-proof, 
non-metallic  receptacle  and  diluted  witli  water,  about  equal  volumes  having 
been  found  to  give  the  besl  results.  After  cooling,  the  picric  acid,  which 
separates  usually  in  large  crystals,  is  filtered  by  means  of  "  nutches  "  or 
centrifuges,  and  washed.  The  yield  is  somewhat  less  than  the  theoretical. 
The  formation  of  too  large  crystals  and  "  caking  "  should  be  prevented.  It 
is  now  usually  of  sufficient  purity,  but  to  obtain  it  still  purer,  it  may  be  fused 
in  a  steam-jacketed  enamelled  kettle,  from  which  it  is  run,  if  desired,  through 
a  sieve  of  platinum  or  gold,  into  a  wooden  tank  with  water.  It  is  then  filtered 
off  again.  The  method  suggested  in  the  literature  of  dissolving  in  alkali, 
and  again  precipitating,  is  irrational  and  dangerous,  and  lias  never  been 
practised  by  manufacturers. 

The  material  of  which  the  nitrators  are  made  may  be  cast-iron  if  the 
strength  of  the  acid  is  always  kept  above  82-S5  per  cent.,  otherwise  earthen- 
ware or  enamel  receptacles  are  indispensable.  After  the  nitration  the  mixture 
is  diluted,  and  for  all  final  operations,  contact  with  metals,  other  than  precious, 
must  be  avoided.1  Coatings  of  a  pure  asphaltum  varnish  have  given  satis- 
faction. Proper  agitation  devices  and  ready  means  for  discharging  the 
nitrators  and  filling  the  same  open  a  wide  field  for  the  ingenuity  of  the  con- 
structional engineer. 

The  largest  manufacturer  of  picric  acid  in  the  world  (Hauff  in  Fuerbach) 
uses  an  interesting  and  highly  efficient  filtering  device.  It  consists  of  a  filtering 
box  or  "  nutch,"  with  vacuum  below  and  above,  and  is  adapted  to  be  used 
as  both  filter  and  dryer.  The  crude  picric  acid  is  placed  on  the  filtering 
surface  (a  porous  stone  plate)  and  suction  is  applied.  After  the  bulk  of  the 
adhering  waste  acid  has  been  removed,  alcohol  is  sprayed  on  the  material 
and  received  in  a  separate  container,  from  which  it  is  at  once  rectified  and 
recovered.  The  filter  box  is  then  covered  with  a  specially  constructed  lid 
and  vacuum  applied;  the  drying  proceeds  very  raj. idly,  and  the  resulting 
product  is  very  pure,  due  to  the  fact  that  it  has  been  washed  with  alcohol, 
which  is  an  excellent  solvent  for  the  resinous  products  always  formed  during 
high  nitration. 

Picric  acid  forms  pale  yellow,  crystalline  needles  or  scales,  of  an  intensely  Properties, 
bitter  taste  and  specific  gravity  1*767  at  10°.     The  pure  acid   melts   at    122°, 
and  the  common  at  a  lower  temperature,  to  a  brownish-yellow  oil,  which  at 

1  Tin  and   aluminium  may   be  used.      A.   M. 


280  EXPL<»IYHS 

a  higher  temperature  partially  Bublimes,  and  boils  with  formation  of  yellow, 
bitter,  suffocating  vapours.  The  lower  melting-point  of  impure  picric  a< id 
is  probably  due  to  an  admixture  of  dinitro-phenols  or  of  a  nitro-cresol.  Hence 
the  melting-point  ol  picric  acid  is  a  test  of  its  purity. 

When  strongly  heated,  picric  acid  burns  rapidly  with  formation  of  an 
intensely  black  smoke.  It  does  not  explode  when  heated  under  ordinary 
conditions,  but  it  can  be  made  to  explode  by  allowing  it  to  fall  into  a  tube 
heated  to  a  red  heat.1  Picric  acid  can  be  detonated  by  means  of  other  violent 
explosives  ;  a  charge  of  1  g.  of  mercury  fulminate  suffices  to  determine  the 
explosion  under  favourable  conditions.  Metallic  picrates,  especially  that  of 
lead,  or  even  an  imperfect  mixture  of  picric  acid  with  the  oxides  or  nitrates, 
will  detonate  violently  when  heated  or  submitted  to  a  moderate  blow,  and 
the  explosion  Mill  induce  the  detonation  of  neighbouring  quantities  of  picric 
a<id  or  picrates,  even  though  they  be  ^et.  In  spite  of  the  comparative 
insensitiveness  <>f  the  pure  substance,  these  properties  have  led  to  a  number 
of  serious  accidents,  of  which  the  following  Mere  particularly  disastrous  : 
Heron  Chemical  Works.  Lancaster,  June  7,  1882.2 

Roberts,  Dale  and  Co.'s   Works,  Cornbrook,  near  Manchester,  June   -'-' 
18s: 

Rheinau,  near  Mannheim,  June  27,  1890. 4 
Read,  Holliday  and  Sons,  Huddersfield,  May  30,  1900.5 
( .liesheim-Elektron,  near  Frankfort  a.  Main.  April  25,  1901,  twenty-four 
killed  and  one  hundred  and  seventy-eight  injured.6 

Woolwich  Arsenal,  June  18,  1903,  sixteen  killed  and  fourteen  injured.'1 
For  the  historical  development  of  the  use  of  picric  acid  as  an  explosive, 
see  Chapter  ill,  pp.  44,  49.  It  is  now  used  only  as  a  military  explosive  either 
alone  or  mixed  with  a  nitrate  or  with  other  nitro-compounds.  It  is  not 
itself  used  much  as  a  dye  now.  but  it  i>  used  in  the  manufacture  of  more  complex 
compounds,  which  are  valuable  dye-stuff-. 

The  sensitiveness  of  picric  acid  can  be  reduced  by  mixing  it  with  inert 
substances.  Under  Orders  in  Council.  Nos.  20  and  20a,  it  is  not  considered 
an  explosive  when  mixed  with  half  its  weight  of  water  or  with  three  times 
it>  weight  of  the  following  substances  :  anhydrous  sulphate  of  soda,  crystallized 
sulphate  of  soda  when  in  hermetically  closed  packages,  <>i  potash  alum.8  It 
i-  also  not   considered  an  explosive  if  in  a   quantity  of  not  exceeding  Juno  lb, 

1  II  Berthelot,  Arm.  Chim.  Phya.,  1889,  vol.  xvi..  p.  23  ;  P.  et  8.,  1900,  vol.  x.,  p.  280. 

S.B.,  si.   i>.  20,  Home  Office   Papers  A.   17.412. 
■■>  >./,'..    Jl.  '  A.J!..    Is'."',   p.   4S.  '  >./,'..    139. 

•■  Ang.,  1901,  p.  459;   Chem.  Zeit.,  May  1.  1901  ;   Chem.  Trad*  Jour.,  May  is  and 
25,   1901   (Chemical  N< 

7  A.l:..   1103,  p.  51;    Chem.  Trad*   Jour.,  July  4.   1W3. 
"    -  ■     thi    Explosives  Act,  pp.  204—208. 


OTHER  NITRO-AROMATIC  COMPOUNDS  281 

packed  in    substantial   barrels   or   cases   where  it   is  not   liable  to  come   in 

contact  with  any  metal  other  than  aluminium,  nor  with  the  oxides  or  other 

compounds  (other  than  sulphates)  of  lead,  iron,  potassium,  barium,  calcium, 

sodium,  zinc  or  copper,  nor  with  any  chlorate,  nitrate,  or  other  oxidizing  agent. 

Other  trinitro-phenols  are  known,  but  they  are  not  made  so  easily,  and  Higher 

•     ,  ,       ,  !  ,  TT.    ,  -,iii  ii  i      nitro-phenol 

are  probably  less  stable.     Higher  nitro-phenols   have  also   been  prepared  : 

thus  J.  J.  Blanksma  l  by  nitrating  meta-nitro-phenol  with  mixed  acid  in 

the  cold  obtained    2:3:4:  5-tetra-nitro-phenol,   which  melted  at  140°  and 

exploded  at  a  higher  temperature,  but  according  to  R.  Nietzki  2  this  compound 

melts  at  130°,  often  with  a  somewhat  violent  explosion.     In  a  similar  manner 

Blanksma    obtained    pentanitro-phenol    from    2  :  4-dinitro-phenol.       These 

substances  are  not  very  stable  and  are  converted  by  boiling  with  water  into 

trinitro-resorcinol  and   trinitro-phloroglucinol  respectively. 

OH  OH 

N02  y  N02l        In02 

NO 2  NO 2 

OH  OH  OH 

no2,//\no2  NO  2  i^N  NO  2 

NO,1        IN02  N02l      Jn02  OH  I    JoH 

N02  N02 

Styphnic  acid  or  2  :  4  :  6-trinitro-resorcinol  is  made  by  nitrating  resorcinol  Styphnic 
or  some  of  its  derivatives.  Resorcinol,  or  meta-dihydroxy-benzene,  can  be  qh 'n  0 
made  from  benzene  in  the  same  way  as  synthetic  phenol,  but  its  derivatives 
occur  in  many  gums  and  wood  extracts,  and  these  can  be  made  to  yield  styphnic 
acid  directly  by  appropriate  treatment  with  nitric  acid.3  Bottger  and  Will 
obtained  a  yield  of  18  per  cent,  from  Brazil  wood  extract  (Fernambukholz- 
extrakt).4 

Styphnic  acid  is  a  fairly  strong  dibasic  acid,  and  its  salts  are  more  violently 
explosive  than  those  of  picric  acid.  Its  use  as  an  explosive  was  patented  by 
Hauff  in  1894,  and  in  1897  it  was  examined  by  the  French  Commission  des 
Substances  Explosives,5  who  found  that  it  was  less  powerful  and  more  expensive 
than  picric  acid,  over  which  it  possessed  no  advantage.  It  does  not  appeal 
ever  to  have  been  used  commercially  as  an  explosive,  but  is  worthy  of  notice 

1  Proc.   K.  Akad.    Witoiscli.,  Amsterdam,   1902,  p.  437. 

2  Ber.,   1897,  p.   181. 

3  See  Stenhouse,  Annate  n,  vol.  cxiv.,  p.   224. 

4  Annul,  n,  vol.  lviii.,  pp.  269,  298.  5  P.  et  S.,  vol.  ix,  p.   139. 


282 


EXPLOSIVES 


in  consequence  of  its  formation  directly  from  natural  product-.     It- melting- 
point  is  175  "'  . 

OH 


NO, 


Trinitro-  In  commercial  cresol  obtained  from  coal  tar  there  are  three  c  resets  pn 

crH°OH,CH,    m  a00llt  Tne  following  proportion 

so' 


Proportion 

Melting- 
point 

Boiling- 
point 

Ortho           ....                    4" 
Meta          ....                35 
Para             ....                   25 

-4 
36 

190* 

_  0-5 

aoi-i 

Mono-  and  di-nitro-compounds  can  be  made  from  all  of  these,  but  only 
meta-cresol  gives  a  trinitro-derivative,  the  others  on  continued  nitration 
being  oxidized  to  oxalic  acid.  etc.  It  is  necessary,  therefore,  to  use  meta- 
1  as  pnre  as  practicable  for  the  manufacture  of  trinitro-cresol.  The 
ortho-compound  can  be  eliminated  by  fractional  distillation  without  great 
difficulty,  but  the  others  boil  at  almost  the  same  temperature.  Nevertheless 
it  is  -aid  that  the  meta -compound  can  be  obtained  almost  pnre  by  fractional 
distillation.1  The  separation  can  also  be  effected  by  sulphonation  with 
oleum,  whereby  meta-cresol  is  converted  into  a  liquid  sulphonic  acid  and 
the  para-compound  into  a  solid  one.  For  other  method-  of  separation  a 
Thorpe's  Dictionary  of  Applied  Chemistry,  vol.  ii..  p.  164. 

Trinitro-cresol  is  made  in  the  same  way  as  picric  acid,  but  the  nitration 
proceeds  with  greater  ease.  The  yield  from  meta-cresol  is  said  to  be  150  per 
cent.,  the  theoretical  l>.-ini_r  22r>  per  cent. 


NO 


Trinitro-cresol  or  trinitro-cresylic  acid  is  a  very  similar  substance  to  picric 
acid,  but  is  less  powerful  as  an  explosive  as  it  contains  a  -mailer  proportion 
of  exygen.     It  has  been  used  in  France  under  the  name  of  (  re-ylite  for  filling 

1  vennin  et  Cheeneau,  p.  280. 


OTHER  NITRO-AROMATIC  COMPOUNDS 


283 


cresylates. 


shell  in  admixture  with  picric  acid.     A  mixture  of  GO  parts  with  40  parts  of 
picric  acid  (melinite)  melts  at  85°  and  is  plastic  at  05°  or  70°. 

The  composition  and  temperatures  of  ignition  of  a  large  number  of  metallic  Picrates  an 
picrates  were  investigated  by  Silberrad  and  Phillips,1  and  the  formation  and  ** 
explosibility  of  various  picrates  and  trinitro-cresylates  by  Kast.2  The  picrates 
of  lead,  calcium,  barium,  potassium,  and  copper  explode  when  heated,  the 
lead  compound  being  much  more  violent  than  the  others.  The  picrates  of 
sodium,  zinc,  silver,  magnesium  and  iron  explode  with  considerably  less 
violence  ;  those  of  ammonium,  mercury  and  aluminium,  like  picric  acid  itself, 
do  not  explode  when  heated  in  the  ordinary  way. 

The  trinitro-cresylates  behave  very  similarly  to  the  corresponding  picrates. 
The  lead  salts  are  also  by  far  the  most  sensitive  to  blows,  being  about  as 
dangerous  in  this  respect  as  nit  ro -glycerine,  blasting  gelatine  and  dry  gun- 
cotton.  The  salts  of  the  other  heavy  metals,  such  as  copper,  silver,  iron, 
calcium,  and  barium  are  also  somewhat  sensitive  :  more  so  than  picric  acid. 
The  salts  of  sodium,  potassium  and  ammonium  are  less  sensitive,  and  those 
containing  water  of  crystallization  are  less  so  than  the  dried  substances. 

The  action  of  solutions  of  picric  acid  and  trinitro-cresol  upon  different 
metals  was  investigated  by  Kast.  Plates  of  metal  5  X  10  cm.  were  placed 
in  mixtures  of  50  g.  picric  acid  or  trinitro-cresol  and  200  g.  water  for  four 
weeks  It  was  then  found  that  the  following  quantities  of  the  metals  had 
been  dissolved  : 


Picric  acid 

Tri-nitro-cresol 

Lead     . 

.       3-91  g. 

4-15  g. 

Iron 

.      13-71  g. 

3-78  g. 

Zinc 

.      18-86  g. 

0-48  g. 

Copper 

.        2-37  g. 

1-04  g. 

Brass    . 

.        1-19  g. 

1-02  g. 

Aluminium    . 

.small  quantity 

small  quantity 

Saposhnikof  tried  the  effect  of  molten  picric  acid  on  metals  under  conditions 
more  nearly  resembling  those  that  prevail  in  a  shell  that  is  filled  with  the 
melted  explosive.3  One  gramme  of  the  finely  divided  metal  was  placed  in  a 
beaker  with  2  g.  of  picric  acid  and  kept  at  a  temperature  of  125°  for  eight 
and  a  half  to  nine  hours.     The  weights  of  metal  that  had  been  dissolved  were  : 


Lead 

Iron . 

Zinc 

Copper 

Aluminium 

Nickel 

Tin  . 


0-2798  g. 
01530  g. 
0-2046  g. 
017:.  l 
0-0488  g. 
0-1862  g. 


1  J.C.S.,  Trans.,    1908,  p.  474.  2  S.S.,    1911,  pp.   7,   31   and   67. 

3  J.  Saposhnikof,  S.S.,   1911,  p.   183. 


EXPLOSIVES 

Pic-rates  were  at  one  time  much  favoured  by  invent  ingredients  of 

exp>l   -  ait  very  few  of  thc>e  mix!  ieved  any  practical   - 

;*>wder        -    "  tase     m  picrate  and  saltpetre  and  sometimes 

charcoal,  and  was  made  for  a  time  in  France  as  a  cannon  powder.     Bru;_ 
powder         aisted       54         ts  Jim  picrate  and  4»',  (,f  saltpetre,  and 

-  said  to  give  good  re>ult<  in  the  pot  rifle.     A  mixture  of  43  parts 

ammonium  picrate  and  57  saltpetre  is  osi  ting  agent  in  lyddite 

shell,  under  the  name  of  picric  powder.     It   i>  made  by  incorporating  the 
two  ingredients  together  in  a  ball  mill. 

vie  by  con  -  _  phenol  or  sodium  phenate  with  methyl 
chloride  or  methyl  alcohol  in  various  way>.  Experiments  on  nitrating  it 
have  been  carried  out  by  A.  L.  Broadbent  and  F.  Sparre,1  who  found  that 
there  is  a  tendency  for  the  acid  to  attack  the  side  chain  and  consequently 
give  low  viel  .  ommencing  the  nitration  with  mixed  acids  at  < > : .  however, 

they  obtained  a  yieM       35       r  cent,  of  the  theoretical.     When  one  nitro-group 

been  introduced  into  the  molecule  there  is  no  longer  any  tendency  t<» 
attack  the  side  chain. 

Another  possible  method  of  manufacture  is  from  nitro-phenol.  Phenol 
is  nitrated  in  the  cold  with  dilute  nitric  acid,  yielding  ortho-  and  para-nitro- 
phenol  and  some  tar.  The  ortho-compound  is  distilled  off  with  steam  and 
used  for  the  manufacture  of  dyes.  etc.     The  para-nitro-phenol  is  purified  by 

-allization  from  xylene  ;  it  is  used  for  the  manufacture  of  phenacetin 
and  some  other  synthetic  compounds,  but  the  demand  for  it  i-  less  than  for 
the  ortho-compound  -  quently  there  is  spare  material,  which  can  be 

for  the  manufacture  of  explosives.  By  treatment  with  caustic  soda, 
sodium  carbonate,  methyl  alcohol  and  methyl  chloride  under  pressure  it  can 
be  converted  into  nitro-anisole,2  which  on  nitration  gives  trinitro-anisole. 

I  »H  OCH3 


NO,  NO, 

Trinitro-anisole  is  a  yellow  crystalline  substance  with  a  melting-point  of 

ific  gravity 'of  1*408  at  20°.     It  has  ti     aami  ntion 

initro-eresol.  but   is  free  from  acid  character  and  consequently  much 

safer,  but  unfortunately  it  is  slowly  hydrolysed  by  water  to  picric  acid.     It 

•re  difficult  to  detonate  than  trotyl.3     It  has  been  used  by  the  Germans 

for  filling  bombs.      In   December    1014   th<  in   Railway   Commission 

admitted  it  to  Groi::  t  their  classification,  enabling  it  to    be    sent    in 

1  Eighth  Intern.  Cong.  Appl.  Chc-m..  vol.  iv..   ;  .    15. 

-    -      ...   Paul.  A  -  587,  3  ?JS  .14*14,  p. 


OTHER    NITRO-AROMATIC   COMPOUNDS 


285 


unlimited  quantities  as  ordinary  goods.     Previous  to  that  date  it  had  not 
been  mentioned  in  the  classification. 

It  is  evident  from  what  has  been  said  above  that  on  nitration  the  NO  2  groups  Kinetics  of 
tend  always  to  take  up  the  meta-position  with  respect  to  one  another,  and  that  mtrat,on- 
when  so  placed  they  are  more  stable  than  when  in  the  ortho-  or  para-position. 
Consequently  in  all  the  important  trinitro-compounds  the  three  groups  are 
arranged  symmetrically  round  the  benzene  ring.  When  the  N02-groups  are 
next  to  one  another  (ortho-position)  there  is  a  tendency  for  one  of  them  to  be  dis- 
placed with  ease,  and  when  three  of  them  are  together  the  middle  one  splits  off 
very  readily.  On  the  other  hand,  the  NO  ,-groups  tend  to  take  up  the  ortho-  or 
para-position  with  respect  to  substituting  groups  such  as  CH3,  OCH3,  OH  and 
NH ,,  and  the  presence  of  these  groups  makes  the  nitration  more  easy  and  rapid. 

The  kinetics  of  the  nitration  reaction  have  been  investigated  by  H.  Martin- 
sen,  who  has  found  that  in  sulphuric  acid  the  velocity  of  nitration  of  nitro- 
benzene is  proportional  both  to  the  quantity  of  nitric  acid  and  of  nitro-benzene- 
present.1  It  is  trebled  for  a  rise  of  temperature  of  10°,  and  is  at  a  maximum 
when  the  molecular  proportion  of  sulphuric  acid  to  water  is  1  :  0*7,  as  is  shown 
by  the  following  figures  : 


Per  cent,  by  weight  of  H20  or  S03  in  acid 

Velocity  at  0° 

Constant  at  25° 

3-2  per  cent,  S03     .... 

5-2         „           H20    .... 
13-7          „                „      . 
15-9         „                „      . 

0-036 

0-085 
0-280 
0-017 

0-22 
1-50 
3-22 
0-18 

The  velocity  of  nitration  is  much  modified  by  the  presence  of  other  atoms 
or  groups  in  substitution  for  the  hydrogen  of  benzene.  Martinsen  gives  the 
following  scheme  : 

N02  >  803H  >  C02H  >  CI  <  CH3  <  OCH3  <  OC2H5  <  OH 

Cl  sometimes  accelerates  and  sometimes  retards  nitration  ;  those  on  the 
right  accelerate,  the  further  they  are  to  the  right  the  more  they  accelerate  ; 
those  on  the  left  retard,  N02  most  of  all.  The  latter  cane  the  NO,-groups 
to  take  up  the  meta-position,  and  those  on  the  light  the  ortho-  and  para- 
positions.2     J.  P.  Wibaut3  gives  the  following  velocities  of  nitration: 


Benzene 

Ohlorbenzene 

Brombenzene 

Toluene 


0-002.")  at    25° 
0-0020       „ 
0-0013 
00080  at  0° 


1  Zeit.  physikal.   Choi,.,    1!)04.  vol.   1..   |».   385. 

2  Ibid.,  1907,  vol.  lix.,  p.  605.  :t  Bee.  (rov,  chim.,   1915.  p.  241 


286  EXPLOSIVES 

Martinson  found  that  when  para-mtro-anilinc  is  nitrated  two.  nitro-groups 
are  introduced  at  nearly  the  same  rate  giving  picramide.  2:4:  (i-trinitro-aniline. 
The  rate  of  nitration  of  .i-nitro-naphthalenc  La  greater  than  that  of  nitrobenzene. 

If  para-nitro-anisole  l>e  freshly  dissolved  in  sulphuric  acid  and  nitric  acid 
be  then  added,  one  molecule  of  the  latter  is  taken  op  instantaneously  with 
the  formation  of  dinitro-anisole.  But  if  the  sulphuric  acid  be  allowed  to 
stand  for  a  day  before  the  nitric  acid  is  added  nitration  is  slow.  This  is 
ascribed  to  the  gradual  formation  of  the  sulphonic  acid,  which  is  much  more 
difficult  to  nitrate.  Sulphonation  of  para-nitro-toluene  is  much  slower  than 
nitration,  but  is  more  rapid  the  stronger  the  acid.  In  oleum  containing 
2*5  per  cent.  S03  the  velocity  constant  is  0003  and  in  absolute  H2S04  0*0004, 
and  in  acid  containing  a  little  water  much  less.1 

In  aqueous  solution  the  nitration  proceeds  in  quite  a  different  way  to 
that  in  sulphuric  acid  solution.  It  commences  very  slowly  and  then  the 
velocity  increases,  being  accelerated  by  the  production  of  nitrous  acid  in  the 
course  of  the  reaction.  The  velocity  of  nitration  is  increased  by  the  addition 
of  sulphuric  acid  or  potassium  nitrate,  and  to  a  less  extent  by  sodium  or 
strontium  nitrate.  A  minute  quantity  of  sodium  nitrite  at  the  commencement 
of  the  reaction  accelerates  it  considerably.2 

1  Zilt.  physikal  Chem.,  1908,  vol.  lxii.,  p.  713. 

2  H.  Martinsen,   ibid.,   1904,  vol.  L,  p.   385. 


PART  VII 

SMOKELESS  POWDERS 


CHAPTER  XXI 
SLOW-BURNING  SMOKELESS  POWDERS 

Drying  the  nitro  cellulose  :  Alcoholizing:  Incorporation:  Shaping  the  powder, 

Poudre  B  :  Russian  powder  :  Rumanian  powder  :  Belgian  powder  :  American 
powder  :  Spanish  powder  :  Ballistite  :  Filite  :  Solenite  :  German  powders  : 
Cordite  :  Weighing  the  gun-cotton  :  Measuring  the  nitro-glycerine  :  Mixing  : 
Incorporating  :    Pressing  :    Drying  :    Japanese  powder  :    Sporting  rifle  powders  : 

Axite  :    Modditc 

All  smokeless  powders  that  have  been  manufactured  up  to  the  present  have 
one  important  feature  in  common  :  every  one  of  them  consists  largely  of 
nitro-cellulose  in  some  form,  and  many  of  them  contain  only  small  proportions 
of  other  substances.  They  may  be  divided  into  two  principal  classes  :  slow- 
burning  powders  for  use  in  rifled  fire-arms,  and  fast-burning  for  use  in  shot- 
guns, etc.  Of  the  former  there  are  two  main  divisions  :  those  that  contain 
nitro-glycerine,  the  nitro-glycerine  powders,  and  those  that  do  not  contain 
it,  which  are  called  nitro-cellulose  powders,  although  all  the  powders  contain 
this  substance.  Powders  for  rifled  fire-arms  are  required  to  burn  at  a  uniform 
rate  and  not  too  fast  ;  this  is  achieved  by  converting  the  nitro-cellulose  into 
a  uniform  and  dense  colloid  by  mixing  it  with  a  solvent.  Sporting  shot-gun 
powders,  on  the  other  hand,  are  required  to  burn  very  rapidly,  and  as  a  rule 
are  only  partially  gelatinized.  For  nitro-glycerine  powders  the  solvent 
generally  used  is  acetone,  as  it  readily  dissolves  all  nitro-cellulose  even  of 
the  highest  degrees  of  nitration,  but  if  the  powder  contain  no  nitro-glycerine 
the  colloid  yielded  by  acetone  is  too  hard  and  brittle.  Consequently  for 
nitro-cellulose  powders  ether-alcohol  is  generally  used,  and  the  nitro-cellulose 
must  be  of  such  a  description  that  it  can  be  gelatinized  by  this  solvent. 

The  nitro-cotton  or  other  form  of  nitro-cellulose  comes  in  the  wet  state  Drying  the 
from  the  factory  where  it  is  made.  For  safety  some  30  per  cent,  or  more 
of  water  is  left  in  it  until  it  is  necessary  to  dry  it  for  further  use.  The 
nitro-cellulose  may  either  be  in  loose  form  as  it  is  taken  from  the  centrifugal, 
in  which  the  greater  part  of  the  water  has  been  extracted,  or  it  may  be  moulded 
into  blocks,  slabs  or  cylinders  by  compressing  it  in  a  hydraulic  press  with  a 
moderate  pressure.  The  advantage  of  moulding  it  is  that  less  dust  is  formed 
vol.  i.  289  19 


290  EXPLOSIVES 

in  the  drying  Btov<  -  and  during  the  operation  of  weighing  the  oitro-celluloee. 
The  drying  is  effected  by  blowing  air  by  means  of  a  fan  through  a  steam 
heater  and  then  into  the  Btove,  The  temperature  of  the  air  entering  the 
stove  should  oot  exceed  60  ('..  nor  the  temperature  inside  the  Btove  40°. 
The  best  arrangement  of  the  inlel  pipe-  i-  t<»  provide  them  with  a  number  of 

orifices  near  the  top  of  the   building  and   to  direct    the  air  on   to  the  ceiling. 

The  outlets  should  be  near  the  floor  and  should  have  a  larger  area  than  the 

inlets.      The  reason  for  blowing  the  hot  air  in  at   the  top  of  the  stove  i-    that 

w  hen  the  air  takes  up  water  vapour  from  the  nitro-cellulose  it  becomes  h<a\  in 

ami  tends  to  sink  ;    although  the  water  vapour  itself  is  lighter  than  the  air, 

the  cooling  produced  by  the  conversion  of  the  water  into  vapour  is  so  great 

that  the  air  after  taking  iij)  the  water  i-  considerably  denser.      Thus  suppose 

l  cubic  metre  of  dry  air  at  40   C.  on  coming  in  contact  with  the  wet  gun-cotton 

to  take  up   1   gramme  of  water.     The  latent  heat  of  water  vapour  at   this 

temperature  is  573  calories  per  g.,  the  cubic  metre  of  air  weighs  1127 

and  it-  specific  heat  is  n-2:>7  calories  per  g.     Consequently  the  reduction  of 

5  7 : ; 
temperature   of   the   air   i-  =  2*14c    and  the  volume   is   reduced 

1127  X    237 

to  993*2  litre-.     The  gramme  of  water  vapour  occupies  a  space  of  1-4  litre, 

and  therefore  the  1  li's-.")  g.  of  the  damp  air  occupies  994*6  litres,  and  a  cubic 
metre  of  it  weighs  1 134*6  g.  Hence  by  taking  up  this  small  amount  of  moisture 
the  density  of  the  air  has  been  increased  0*63  per  cent.  :  the  evaporation 
of  more  water  will  lead  to  a  further  increase  of  density.  It  is  important 
that  the  inlets  and  outlets  he  well  distributed  round  the  ceiling  and  floor 
respectively  to  avoid  the  formation  of  dead  corners  in  which  the  gun-cotton 
will  not  Ik-  dried  properly.  If  the  air  is  blown  in  at  the  bottom,  as  i.-  often 
the  case,  the  fresh  dry  air  tends  to  rise  at  once  to  the  top  and  escape  through 
the  outlets  before  it  ha-  done  a-  much  drying  a-  it  should.  The  stove  should 
not  he  uniK  cessarily  tall  ;  inside  it  should  be  lined  throughout  with  zinc  sheet 
with  soldered  joints  or  other  suitable  material,  in  order  that  there  shall  be 
no  ciaek-  in  which  dust  may  accumulate,  and  so  that  the  stove  can  be  washed 
out  thoroughly  from  time  to  time.  If  the  nitro-cellulose  ha-  been  moulded 
into  block-,  these  should  be  stood  on  racks  with  air  spaces  between  the  blocks 
to  facilitate  diving.  H  the  material  is  in  the  form  of  loose  fibres,  it  should 
be  laid  on  tray-,  preferably  of  copper  wire.  In  either  case  the  racks  or  trays 
should  be  SO  arranged  that  they  are  connected  electrically  to  earth,  a-  dry 
nitro-cellulose  is  very  liable  to  become  electrified,  and  a  spark  may  set  the 
powdery  material  alight.  The  stoves  should  not  be  very  near  other  buildings, 
a-  there  i-  always  a  risk  of  one  catching  tire.  The  stove-  are  generally 
constructed  of  light  material.  If  the  nitro-cellulose  be  in  Loose  fibrous  form, 
it  may  be  dried  in  twenty-four  hours,  but  if  it  be  moulded,  it  will  take  several 
days.      The   greatest    care   nm-t    he   exercised    not    to   subject    the   dry   nitro- 


SLOW-BURNING  SMOKELESS    POWDERS  291 

cellulose  to  friction  or  blows,  especially  if  it  be  still  warm.     The  whole  stove 
should  be  allowed  to  cool  down  thoroughly  before  it  is  unloaded. 

In  most  instances,  when  an  accident  lias  occurred  in  a  gun-cotton  stove 
the  explosive  has  merely  burnt  away  extremely  fiercely,  but  without  exploding- 


Fig.  -54.     Alcohol  Displacement  Plant  (Maschinenbau  A.-G.  Golzern-Grimma) 

but  on  March  10  and  28,  1913,  severe  explosions  took  place  in  stoves  situated 
respectively  at  Ardeer,  in  Scotland,  and  Pitsea,  in  Essex.1  In  both  cases 
the  stoves  were  being  unloaded,  and  the  presumption  is  that  some  of  the 
gun-cotton  must  have  been  subjected  to  blows  or  friction  by  the  workmen. 
In  the  former  case  it  is  supposed  that  the  explosion  was  brought  about  by 
upsetting  one  of  the  racks  on  which  the  gun-cotton  primers  were  placed.  The 
explosion  caused  three  other  similar  stoves  in  the  neighbourhood  to  explode 
also,  with  the  result  that  altogether  seven  men  were  killed  and  ten  injured. 

1  S.R.,  Nos,  206,  207. 


292 


EXPLOSIVES 


The  explosion  of  these  other  stoves  was  probably  caused  by  the  buildings 

being  shaken  and  wrecked,  and  perhaps  by  the  racks  being  thrown  down  in 

them  also.     Prom  this  accidenl  the  deduction  may  be  drawn  that  these  and 

all    other    lniililiiiLr-    for    sensitive  explosii 

should    be  bo  strongly  constructed   that    the 

explosion  of  a  neighbouring  building  will  not 

wreck  them.    The  racks  should  be  fixed  rigidly 

t<»  the  Moor. 

In  the  case  "f  powders  that  are  gelatinize  d 

with  ether-alcohol  the  troublesome  ami  dang*  ir- 
ons operation  of  drying  the  oitro-cellulosi 

be  dispensed   with,  a-  the  water  can   be  di— 

placed  by    means  of  alcohol.     The   wet   gun- 

cotton  i<  packed  into  a  cylinder  (act    Pig.  ~<4  . 

ami    then    alcohol    i-    forced    through    it    by 

mean-  of  compressed  air.  First,  water  flows 
away  and  i>  run  to  waste,  then  weak  alcohol, 
which    i-    re-rectified,  so    that    it    can    be 

used  again,  and.  finally,  fairly  >troiiLr 
alcohol,  which  i-  used  again  for  the  pre- 
liminary displacement  of  another  cylindi  r 
of  nitro-cellulose.  The  alcohol  i-  always 
introduced  at  the  t<»)»  of  the  cylinder  as 
it  i-  lighter  than  the  water  ;  first  alcohol 
from  the  final  displacement  in  another 
cylinder,  and  then  strong  alcohol.  The 
displacement  take-  three  to  six  hours. 
When  the  water  ha-  been  displaced,  the 
-urplu-  alcohol  is  removed  from  the  nitro- 
cellulose by  means  of  a  hydraulic  press.  A 
type  of  pressmuch  used  for  this  purpose  in 

Germany  i-  Bhown  in   Pig.  55.      Tt  has  two  cylinder-,  which  swing  round 

_  ther  on  one  of  the  columns,  so  that  whilst  the  content-  of  one  are  being 

pressed,  the  other  can  be  emptied  and  rilled  again.     Washing  with  alcohol 

ha-  the  further  advantage  that  it  removes  the  unstable  impurities  to  >ome 

at.     According  to  Guttmann  tin-  device  of  displacing  water  by  alcohol 

was  used  in  Austria  in  1891,  hut  the  invention  ha-  been  claimed  for  Messier, 

oieur  dea  Poudres  el  Salpetres,  in  1892.     In  this  year  a  patent  was  also 

taken  out  for  it  in  England  by  Durnford.1 

The  oitro-cellulose  i-  incorporated  with  the  solvent  in  a  machine  which 

1  Mo  ii..  | p.  L':)'.t.     Vennin,  Poudres  <t  Explotifs,  p.  394; 

Bui-  ;..  :;:.     Brit.  1'at.  20,880  of  Nov.  IT.  L892 


Pn  • 


-  far  Alcoholized  Nitro- 
cellulose 


SLOW-BURNING   SMOKELESS   POWDERS  293 

is  constructed  on  the  same  principles  as  the  kneading  machines  used  in  bakeries 
(sec  Pigs.  56,  57).  It  consists  of  a  trough,  in  which  two  curved  blades  rotate 
in  opposite  directions,  one  twice  as  fast  as  the  other,  Loth  going  Hownwards 
in  the  centre  of  the  trough  and  upwards  by  the  walls.  First,  some  of  the 
solvent  is  poured  in  to  moisten  the  axles  and  blades,  then  the  nitrocellulose 
and  ..thci'  materials,  and  finally  more  solvent.  The  incorporator  is  then 
started  and  kept  running  for  some  hours  until  the  constituents  of  the  powder 


Fir: 


56.      Incorporating  Machine  in  Working  Position 
(Werner.  Pfleiderer  and  Perkins,  Ltd.) 


are  thoroughly  mixed,  the  trough  meantime  being  kept  covered  to  prevent 
loss  of  solvent.  The  trough  is  then  tilted  up  and  the  blades  are  made  to 
rotate  in  the  opposite  direction.  The  dough  falls  into  a  box  or  other  receptacle, 
and  is  taken  to  the  buildings  where  it  is  pressed  into  cords,  tubes  or  strip, 
or  is  rolled  into  -licet,  according  to  the  form  that  it  is  required  to  give  to 
the  finished  powder. 

If  the  incorporator  he  driven  by  an  electric  motor,  this  should  be  placed 
so  that  vapour  <>f  the  solvent  cannot  possibly  be  ignited  by  spark-  of  the 
commutator.  The  motor  should  be  provided  with  an  automatic  release  to 
prevent  danger  of  the  explosive  being  fired  by  the  application  of  too  much 
power.  The  lid  of  the  incorporator  i-  best  made  of  aluminium,  domed  some- 
what   so   as   to   allow    of   more   material    being   placed    in    the   machine.     The 


EXPLOSIVES 


aluminium  may  be  surrounded  by  a  wooden  frame  held  down  to  the  rim  <>f 
the  incorporator  by  butterfly  nuts. 
haping  the  '{-|lt.  dough  i>  next  formed  into  the  desired  Bhape.     Formerly  it  was  in 

many  cases  rolled  into  sheets  by  passing  it  repeatedly  through  rolls  resembling 


57.     Incorporating  Machine.     Trough  Tilted,  showing  Blades 


a  paper-maker's  calender.  The  sheets  were  cut  into  strips,  which  were  again 
cut  transversely  so  as  to  form  cubes  or  flakes.  Now  it  is  more  usual  to  press 
the  dough  through  a  die  in  a  press,  which  is  an  adaptation  of  the  machine 
used  for  making  macaroni.  It  i-  thus  obtained  in  the  form  of  cud-,  strips,  or 
tubes  :  it  desired  these  can  then  be  cut  into  flakes  of  any  required  thickness. 
Poudre  B.  which  was  invented  by  vleille  and  adopted  by  the  French 
Government  in  1884  for  use  in  the  Lebel  rifle,  was  the  first  smokeless  powder 
to  achieve  Buccess  in  a  rilled  lire-arm.  It  is  named  after  the  first  letter  in 
the  name  of  ( reneral  Boulanger,  who  was  Minister  of  War  at  the  time.  Accord- 
ing to  an  analysis  made  by  Lieut.  Wisser,   l~ >.\..'  it-  composition  was: 


ible  oitro-celluloee 

.! 'lt- 
Miii 


68-2  pei   oent. 

29-8 
20        „ 


1  Worden.  Udoa    Industry,  \ 


SLOW-BURNING   SMOKELESS   POWDERS 


295 


Apparently  it  was  gelatinized  by  means  of  acetic  ether.     The  composition 
was  modified  several  limes:    the  powder  known  as  Pontile  BN  consisted  of: 


Insoluble  nitrocellulose 

Soluble 

Barium  nitrate    . 

Potassium  nitrate 

Soda  .... 

Volatile  matter    . 


29*1     peX    cent. 

41-3 
190 

8-0 
20 


.'38-7    per   cent  . 

33-2 

18-7 

4-5        „ 

3-6        „ 

13 


N  stands  for  Nonvelle.  Instead  of  soda,  tannin  was  sometimes  used.  The 
powder  was  gelatinized  with  ether-alcohol;  the  first  analysis  was. given  by 
Neumann,1  the  second  by  Weaver.2 

All  other  solid  constituents  were  subsequently  abolished,  and  the  powder 
consisted  only  of  a  mixture  of  soluble  and  insoluble  nitro-cottons  gelatinized 
with  ether-alcohol.  In  order  to  improve  the  stability  an  addition  of 
amyl-alcohol  was  introduced  in  1896-1897,  first  2  per  cent,  and  afterwards 
8  per  cent.  These  powders  received  the  names  B(AM2)  and  B(AM8) 
respectively.     Now  diphenylamine  is  added  instead. 

Various  processes  of  nitration  are  in  use  in  the  French  Government 
factories  :  the  Abel  process,  nitrating  centrifugals,  and  at  Angouleme  there 
is  a  displacement  plant  on  Thomson's  system.  Two  sorts  of  nitro-cotton 
are  made,  called  CPj  and  CP2  respectively.  CPi  is  a  gun-cotton  of  high 
nitration  giving  205  to  215  c.c.  NO  per  gramme  in  the  nitrometer  (=  about 
13  per  cent,  N)  and  having  a  solubility  in  ether-alcohol  of  less  than  15  per 
cent,  :  in  practice  it  gives  209  to  214  c.c.  NO,  and  has  a  solubility  less  than 
10  per  cent.  CP2  is  a  soluble  nitro-cotton  giving  190  to  198  c.c.  NO  per 
gramme  (=  about  12  per  cent,  N),  and  having  a  solubility  of  over  96 per  cent. 
Limits  are  also  set  to  the  viscosity  of  the  solution  in  ether-alcohol  and  to 
the  percentage  of  matter  soluble  in  alcohol. 

The  proportions  of  CPX  and  0P2  are  varied  according  to  the  sort  of  powder 
that  is  to  be  made.  For  rapid  powders,  such  as  BF,  20  to  25  per  cent,  of 
soluble  nitrocellulose  are  used,  and  in  the  slowest  powders  50  to  55  per  cent. 
CPi  is  not  only  a  more  powerful  explosive  than  CP2,  but  as  the  fibres  are 
not  gelatinized  by  the  solvent,  but  only  covered  with  the  solution  of  (T2, 
it  burns  more  rapidly. 

The  nitro-celluloses  are  boiled  and  pulped  and  mixed  in  the  proper 
proportions,  and  are  then  dehydrated  with  alcohol  and  pressed.  If  the 
pressure  l.e  300  kg.  per  sq.  cm.  (2  tons  per  sq.  in.)  the  alcohol  left  in  the  Mock 
amounts  to  aboul  20  or  25  parts  per  100  of  nitro-cotton.  It  is  then  placed 
in  the  incorporator  with  the  solvent,  which  consists  of  1  volume  of  alcohol 
to  1-9  volumes  ether,  allowance  being  made  for  the  alcohol  already 
present,  The  quantity  of  solvent  varies  according  to  the  sort  of  powder 
1  S.S.,  1910,  p.  451.  2  Military  Explosives,  p.  135. 


296  EXPLOSIVES 

from  14<>  to  L50  parts  per  LOO  part-  tiitro-cotton.  The  alcohol  used  is  of 
!•.">  per  cent,  strength  by  volume  (92*5  per  cent,  by  weight,  sp.  gr.  -8104), 
the  ether  is  of  65  Baume  (sp.  gr.  •Ti>ii4).  and  the  mixture  is  of  56°  Baume 
(sp.  i_rr.  -Too).  In  the  solvent  is  dissolved  the  stabilizer,  diphenylamine, 
l  ■.')  to  -  per  cent,  of  the  nitro-cellulose.  The  incorporation  lasts  from  one 
to  three  hours,  and  then  the  dough  is  placed  in  air-tight  boxes  and  allowed 
to   ■•  ripen.*' 

By  means  of  a  press  it  is  now  squirted  through  a  die  which  forms  it  into 
a  -trip.  Above  1  lie  die  is  placed  a  filter  of  fine  wire  gauze  to  retain  impurities. 
The  strip  is  received  on  an  endless  band.  Its  width  varies  according  to  the 
type  of  powder  from  20  to   150  mm.,  and  its  thickness  from  0*6  to  S  mm. 

The  strips  musl  not  be  dried  too  rapidly  at  first,  else  they  will  curl  up. 
A-  they  come  from  the  press  they  have  just  sufficient  tenacity  to  allow  of 
their  being  suspended  from  bars.  Thus  suspended  they  are  introduced  into 
,i  chamber  where  they  first  meet  with  air  partly  saturated  with  vapour  of 
ether-alcohol.  The  bars  can  be  moved  in  the  opposite  direction  to  the  currc  nt 
of  air.  -<>  that  the  Poudre  B  meets  air  ever  less  saturated  with  solvent  vapour. 
The  aii-  may  be  circulated  in  a  closed  circuit  :  after  leaving  the  drying  chamber 
it  passes  through  a  heat  regenerator,  then  through  a  cooling  plant,  which 
is  also  constructed  on  the  regenerative  principle,  and  in  which  the  temperature 
i-  reduced  to  _"  to  — 5  ('.  so  as  to  condense  most  of  the  solvent  vapour. 
After  this  the  air  passes  through  the  heat  regenerator  again,  then  through 
a  heating  coil  and  then  is  driven  by  a  fan  back  into  the  other  end  of  the  drying 
chamber.  The  powder  after  this  preliminary  drying  contains  L5  to  20  per 
cent,  of  solvent,   mostly  alcohol. 

It  is  now  cut  to  the  right  size.  Artillery  powders  are  merely  cut  into 
Lengths,  usually  of  100  to  400  mm.  Rifle  powder  is  cut  into  small  flakes. 
1  5  to  _  nun.  square  and  about  0-5  mm.  thick:  the  strips  are  first  cut  by 
rotating  circular  cutters  into  narrower  strips,  and  these  are  then  cut  trans- 
versely. Irregular  grains  are  sorted  out  by  means  of  automatic  sieves  and 
re  incorporated   with  a  fresh  charge. 

The  cut  powder  is  then  dried  in  stoves  heated  not  above  55°.  Tt  is  next 
immersed  in  water  at  or  slightly  below  80°  C.  for  a  period  varying  from  a 
few  hours  up  to  forty-eight  hours  for  powders  of  the  largest  size.  Finally 
it  is  dried  again  in  a  stove  for  one  to  four  days  to  remove  t  he  water  and  reduce 
the  volatile  matter  within  the  limits  fixed  for  each  soil  of  powder,  0*8  to  2 
per  cent.  The  water  immersion  is  carried  out  at  such  a  high  temperature 
in  older  to  reduce  the  time.  A  reduction  of  10  in  the  temperature  would 
render  it  necessary  to  double  the  time  of  immersion,  and  a  reduction  of  20° 
to  quadruple   it. 

The  powders  are  given  letters  according  to  the  purpose  lor  which  they 
are  intended:    thus  BF  and    BNF  are  small-arm   powders  from   the   words 


Powders 

BM6 

to 

BM, 

BMj 

to 

BM, 

BM9 

to 

BM10 

BM, 

to 

BMia 

BM13 

to 

BM17 

BM„ 

to 

BM,, 

SLOW-Bl'RXIXO   SMOKELESS   POWDERS  297 

"  fusil  "  and  "  nouveau,"  BC  is  powder  for  field  guns,  the  celebrated 
•'  Boixante-quinzes,"    from    " campagne,"    BSP    powder   for   siege    howitzers 

from  "siege  et  place,"  and  BGC  powder  for  the  larger  military  guns  from 
"  gros  calibre."  Powders  for  naval  ordnance  have  the  letter  M  (marine) 
with  an  index  figure  according  to  the  size  : 

Calibre 
mm. 
100  and   138-6     . 

164-7  .... 

L94 

24ii  and   274-4 

305 

340 

In  addition  Letters  and  indicts  are  Used  to  indicate  the  stabilizer  added  and 
the  percentage  :  thus  AM,  means  8  per  cent,  of  amyl-alcohol,  and  IK  2  per 
cent,  of  diphenylamine.  Other  letters  -how  the  place  and  date  of  manufacture 
of  the  powder  and  the  cartridges.  For  instance  BM7,  AM8,  01.  SM,  B.  2,  2 
is  a  naval  powder  with  8  per  cent,  amyl-alcohol  forming  part  of  the  4th  lot  of 
1901  made  at  Saint  Medard  and  put  into  cartridges  at  Brest  in  February, 
1902.  Poudre  BC  is  made  in  strips  measuring  80  mm.  X  40  mm.  X  0-7  mm.  :  the 
width  of  the  largest  naval  powders  is  as  much  as  150  mm.,  and  the  thickness 
8  mm.  Naval  powders  are  blended  into  uniform  lots  of  100  tons  each.  Poudre 
BX.F.  in  use  with  the  I)  bullet,  is  drummed  and  graphited  to  restrain  the 
initial  rate  of  ignition.  On  the  other  hand,  BC,  BSP  and  BM\  to  BMS  are 
striated  to  increase  the  rate  of  burning. 

The  presence  of  numerous  fibres  of  ungelatinized  nitro-cotton  probably 
facilitates  the  oxidation  and  consequent  deterioration  of  Poudre  B.  The 
extent  to  which  it  is  porous  is  indicated  by  the  density,  which  is  only  about 
152,  whereas  that  of  nitro-cotton  is  1G7.  In  former  years  a  number  of 
spontaneous  ignitions  occurred  with  Poudre  B.  of  which  those  on  the  battleship 
Jena  in  March  1907.  and  on  the  Libcrte  in  September  1911.  attracted  much 
attention  as  both  occurred  in  Toulon  harbour  and  destroyed  the  vessels  in 
the  sight  of  the  whole  town.  Formerly  amyl-alcohol  Mas  added  to  the  powd(  r 
to  improve  its  stability,  but  this  substance  has  no  great  power  of  absorbing 
nitrogen  oxides,  and  the  final  products  are  acid  and  consequently  injurious. 
Old  powders  were  soaked  in  a  mixture  of  ethyl-  and  amyl-alcohols  to  restore 
their  stability.  This  procedure,  called  "  radoubage,"  was  unsound,  and  was 
given  up  after  the  Jena  disaster  in  favour  of  "  remalaxage,"  which  consisted 
of  reincorporating  the  doubtful  powder  with  ether-alcohol  containing  amyl- 
alcohol.  Further  investigation,  however,  showed  that  the  stability  of  the 
nitro-cellulose  was  not  really  restored  by  this  process,  and  a  few  years  ago 
it  also  was  abolished.  No  material  is  now  reworked  except  quite  new  cuttings, 
etc. 


298 


EXPLOSIVES 


The  cost  of  production  of  Poudre  B  in  1912  was  Fr.  t*»"4ti  per  kg. 

The  quest  ion  of  smokeless  powders  was  referred  by  the  Russian  Government 
to  the  greal  chemisl  Mendeleeff,  who  started  work  upon  the  problem  in  1891 
together  with  a  band  of  able  assistants  in  the  scientific  laboratory  of  the 
navy,  which  was  founded  specially  for  this  purpose.  Mendeleefi  found  that 
it  was  possible  to  make  a  nitro-cotton  totally  soluble  in  ether-alcohol,  which 
had  as  high  a  percentage  of  nitrogen  a>  the  mixture  of  soluble  and  insoluble 
nitro-cottons  used  by  the  French  (set  p.  295).  This,  which  he  called  pyro- 
collodion.  when  gelatinized  with  ether-alcohol  gives  a  much  mure  uniform 
colloid  than  a  powder  like  Poudre  B,  as  may  be  seen  in  the  micro-photographs 
reproduced  in  Fig.    58. 

Pyro-collodion  contains  about  1244  per  cent.  X  and  therefore  has  enough 
oxygen  to  convert  all  the  carbon  into  CO  and  all  the  hydrogen  into  water, 
but  as  a  matter  of  fact  some  COj  and  C'H4  are  always  formed  and  some  of 
the  hydrogen  is  evolved  as  such.  According  to  Buisson,  Russian  powder 
contains  1  per  cent,  of  diphenylamine.  The  general  methods  of  manufacture 
are  similar  to  those  for  Poudre  B.  As  the  productive  power  of  the  Russian 
factories  was  insufficient,  powder  was  often  obtained  from  France  before 
the  war.1 

In  Rumania  a  powder  resembling  Poudre  B  is  made  from  a  mixture 
of  two  nitro-cottons  containing  13  and  125  per  cent.  X  respectively.  At 
a  factory  at  Dudeski  a  powder  is  made  containing  1  per  cent,  of  diphenylamine 
and  4  per  cent,  of  centralite.  which  is  a  substance  used  to  gelatinize  the  BUrface 
of  the  powder  and  so  restrain  the  initial  rate  of  ignition.2 

The  powder  made  by  Coorjal  et  (  ie.  at  (  aidiile  was  also  of  the  same  type. 
It  contained  40  to  60  per  cent,  of  soluble  nitro-cotton  gelatinized  by  means 
of  ether-alcohol  in  the  proportion  of  1125  parts  by  weight  to  1000  pan-  of 
nitro-cotton.  The  dough  was  not  pressed  through  a  die  but  rolled  into  sheets 
between  rollers,  doubled  over  and  rolled  Beveral  times.  The  sheet-  were 
then  cut    into   -nip-,  or  flak- 

The  Americans,  after  experimenting  with  various  Borts,4  have  adopted  a 

1  PrdbUtru   des  Poudres,  p.   70.  2  Ibid.,  p.  59.  3  Ibid.,  p.  63. 

4  The  Maxim-Schupphaus  powders  that  were  used  in  tin-  American  services  had  tin- 
following  compositions  : 

<  inn-cotton       ....... 

Soluble  nitro-cellulose        ..... 

Xitio -glycerine.         ...... 

CTree        ........ 

They  were  gelatinized  by  means  of  acetone. 

The  powder  for  the  naval  small-arms  consisted  of  nitro-cellulose  and  the  nitrates  of 
barium  and  potassium,  that  for  the  military  small-arms  contained  ;•  l-> «  nitro-glyoerine 

and  a  deterrent.     (Weaver,  Military  Explosir, *,   l <*<><;,  p.   i:?4.) 


cenl . 

1  '•     '      '•••lit 

80 

.. 

19-5 

10 

— 

'.» 

M     :, 

1 

SLOW-BURNING  SMOKELESS   POWDERS  290 

pyro-collodion  powder  for  all  kinds  of  guns.1  In  the  United  States  the  powder 
is  made  up  into  the  form  of  short  cylinders  which  are  pierced  longitudinally 
with  small  perforations,  usually  seven.  The  plant  and  methods  of  manu- 
facture are  described  by  Worden.  The  soluble  nitro-cotton  with  126  to 
128   per   cent.   N  is  made  as  described  on  p.  180,   and   boiled  to   render  it 


Pyroxyline  Powder. 
Mixture  of  Soluble  and  Insoluble 
Nitro-cellulose 


Pyro-collodion  Powder 


Fig.  58. 


Microphotographs  of  Smokeless  Powders  (Saposhnikoff,  S.S.,  1907,  p.  163) 
Sections  0-05  mm.  thick.     Magnification  150 


stable.2  The  greater  part  of  the  water  is  wrung  out  in  a  centrifugal,  and 
the  remainder  is  displaced  by  alcohol  in  a  hydraulic  press.  Pressure  up  to 
3500  lb.  to  the  square  inch  is  then  applied  so  as  to  produce  a  block  weighing 
about  38  lb.,  of  which  10  lb.  is  alcohol  of  88  per  cent,  strength.  These  blocks 
are  broken  up  with  wooden  mallets,  and  three  of  them  are  loaded  into  an 
incorporating  machine,  which  is  run  for  about  fifteen  minutes  before  any  ether 
is  added  in  order  that  the  lumps  may  be  broken  up  to  a  fine  powder.  Then 
48-4  lb.  of  ether  are  added  and  6  oz.  of  diphenylamine  to  act  as  a  stabilizer, 
so  that  the  charge  consists  altogether  of  : 

Nitro-cotton 

Alcohol        .... 

Water  .... 

Ether  .... 

Diphenylamine 

The  incorporator  is  kept  covered  to  prevent  loss  of  solvent,  and  incorporation 
is  continued  for  forty-five  minutes.     The  white,  finely  comminuted  material 

1  See  Schiipphaus,  J.  Soc.  Chem.  hid.,  1895,  p.  »->(>;   Hudson  Maxim    ibtd     1897    n 
495;    Aspinwall,  ihid.,   1900,  p.  315.  l 

2  Nitro-celluloae   Industry,  pp.  902  926. 


.      84  lb. 

.     26-4  lb 

3-6    „ 

•      48-4    „ 

G  oz. 

EXPLOSIVES 


i-  then  converted  into  a  compact  mass  by  subjecting  it  to  a  pressure  of  35001b. 

t«>  tlit-  square  inch  in  a  hydraulic  press.  By  means  "f  another  press  it  is 
filtered  through  a  30-mesh  iron  wire  sieve  t<>  remove  gross  impurities,  Then 
it  i-  compacted  again  in  a  third  press,  and  by  means  of  a  fourth  it  i-  squirted 
through  a  die.  which  forms  it  into  a  long  multi-perforated  cord.  The  dough 
-    -  i   -tit!  in  consequence  of  the  small  proportion   <>f  solvent   used  that   a 


Fig.  59. 


rican  Pyro-collodion  Powders  (from  Appleton's  M 


considerable  amount  of  heat  i-  generated  in  passing  through  the  die.  but  by 
mean-  <.f  a  water  jacket  the  temperature  i-  kept  down  t«>  30  or  35°.  It 
is  not  advisable  to  reduce  the  temperature  l»el<>w  30°,  because  at  lower 
temperatures  the  cord  becomes  too  hard  to  he  cut  inT<>  short  lengths  in  the 
next  operation.  In  order  to  prevent  fall  of  temperature  and  evaporation  of 
ether  from  the  warm  colloid,  the  cord  i-  passed  at  once  to  the  powder  cutter. 
whence  the  grain-  drop  into  a  closed  receptacle.  This  i-  removed  to  a  drying 
house,  where  the  drying  i-  carried  out  slowly  at  first  in  order  no.t  t->  distort 
the  grains  too  much  or  make  them  crack.  The  temperature  of  drying  does 
nut  exceed  44  and  the  process  is  a  long  one  :  for  large  grain  powders  it  la>ts 
four  or  five  months.  Quick  drying  methods  are  said  not  t<>  give  a  uniform 
powder.1  The  finished  powder  i-  subjected  t<>  special  physical  tests  t-» 
ascertain  that  it  i-  not  brittle  :  tlM-  ends  of  the  grain  are  cut  off  even  and 
perpendicular  to  the  axis,  and  then  it  i-  subjected  t<»  a  slow  pressure  :  the 
length  must  diminish  4.">  per  cent,  before  the  grain  begins  u<  crack.1  If  kept 
for  long  there  must,  however,  he  a  gradual  though  >1<>w  1<>-s  of  solvent,  which 
will  make  the  grain  harder  and  more  brittle.  If  the  powder  grains  break  up 
in  the  imii.  high  pressures  are  generated,  and  the  gun  may  be  injun  d  <>i  even 

1   P..   Karl.-.  ./ VJS.  .1  tiOery,  Sept.,  Oct.,   1914. 

Schnhmacher,  >'.>'..   1907,  p.   82 


SLOW-BURNING   SMOKELESS   POWDERS  301 

burst.  It  is  stated  that  there  have  been  numerous  cases  of  such  accidents  in 
the  United  States,  but  this  has  been  officially  denied.1  Very  large  quantities 
have,  however,  been  re-worked  with  fresh  solvent  and  an  addition  of  di- 
phenylamine ;  thus  at  the  powder  works  at  Indian  Head  in  1013, 1,800,000 lb. 
of  new  powder  were  made,  and  905,000  lb.  were  re-worked  at  a  cost  35 
per  cent,  of  that  of  the  new  powder.  Altogether  nearly  8,000,000  lb.  had  been 
re-worked  up  to  the  end  of  1910. a  The  quantity  of  solvent  in  the  ordnance 
powders  when  new  varies  from  3  per  cent,  in  that  for  the  1  pr.,  up  to  6-8  per 
cent,  in  that  for  the  3<>  cm.  40 -calibre  gun.  The  specific  gravity  of  the  powder 
is  1-563,8  and  the  cost  of  production  26-.  4d.  per  lb.  To  the  contractors  1-2  lb. 
of  alcohol  is  supplied  for  every  1  lb.  of  powder  accepted.  In  the  finished 
grain  the  length  is  two  and  a  quarter  times  the  diameter,  which  is  ten  times 
the  diameter  of  the  holes.4 

The  French,  Russian,  and  American  Navies  are  the  only  important  ones 
that  use  nitro-cellulose  powders  for  their  large  calibre  guns.  The  other  Powers 
are  of  the  opinion  that  for  this  jmrpose  powders  containing  nitro -glycerine 
offer  decided  advantages,  but  for  the  comparatively  small  field-guns  and  for 
small-arms  every  Power  except  Great  Britain  and  Italy  uses  nitro-cellulose 
powder.  Nitro-cellulose  powders  are  mostly  made  of  soluble  nitro-cotton, 
because  ether-alcohol  gives  a  less  brittle  colloid  than  acetone.  The  powders 
differ  somewhat  as  regards  the  degree  of  nitration,  also  as  to  the  form  of  the 
grains,  some  being  rolled  into  sheets  and  then  cut  into  small  square  flakes, 
others  being  pressed  into  cords  or  tubes  and  cut  off  into  short  lengths  ;  some 
are  coated  with  graphite  and  some  are  not. 

The  Spaniards,  after  trying  a  nitro-cellulose  powder  made  at  the  Rottweil  Spanish 
works  in  Germany,  containing  about  1  per  cent,  of  camphor  and  a  small  pow  er* 
proportion  of  a  urea  derivative,  now  make  their  own  powder,  which  also  is 
of  the  nitro-cellulose  type.     For  small-arms  it  is  made  in  the  form  of  flakes, 
for  artillery  in  long  tubes,  but  they  have  also  experimented  with  powder 
in  strip  form.5 

In  1887,  a  few  years  after  the  invention  of  Poudre  B,  Alfred  Nobel  invented  Ballistite. 
a  smokeless  powder  in  which  the  fibrous  structure  of  the  nitro-cotton  wras 
destroyed  not  by  the  use  of  a  volatile  solvent,  but  by  dissolving  it  in  another 
explosive,  nitro-glycerine.  This  substance,  to  which  he  gave  the  name 
ballistite,  is  indeed  blasting  gelatine  with  the  proportion  of  nitro-cellulose 
largely  increased.6     At  first  benzene  was  added  to  facilitate  the  solution, 

1  S.S.,  1911,  p.  136.  2  S.S.,  1911,  p.   1!»7. 

3  Schuhmacher,  S.S.,   1907,  p.  82.  4  Buisson,  Probleme  des  Poudres,  p.   50. 

5  See  S.S.,  1908,  pp.  154,  248,  283;  1910,  pp.  161,  188,  416;  1912,  p.  479;  from 
Memorial  de  Artilleria,  Feb.  and  Apr.  1908  ;  July,  Sept.,  Oct.,  Nov.,  1909;  July  1912, 
Buisson,  Probleme  des  Poudres,  p.   67. 

6  Fr.  Pats.  185,179  of  1887,  and  199,091  of  1889,  and  Eng.  Pat.   1471  of  1888. 


EXPLOSIVES 


Fig.  60.     American  Rifle  Powder 
(Thorner.  >.>..   1907,  p.    L2 


and  was  afterwards  evaporated  <>tf.  A  better  method  of  incorporation  was 
discovered  by  Lundholm  and  Sayers  l,  who  place  the  soluble nitro-cotton  and 
nitro-glycerine  in  hot  water  and  stir  it  by  means  of  compressed  air.  Under 
these  conditions  the  nitro-cotton  gradually  dissolves  in  the  nitro-glycerine,  or 
perhaps  it  would  be  more  correct  to  Bay  that  the  nitro-glycerine  dissolves  in 
the  nitro-cotton.  The  dough  thus  produced  is  then  passed  between  rolls 
heated  to  50  or  60  <'..  whereby  the  water  i-  pressed  out,  and  the  explosive 
is  made  into  a  sheet.  This  is  folded  over 
and  passed  through  the  rolls  again,  and 
the  operation  is  repeated  until  the 
material  ha-  been  converted  into  a  uni- 
form colloid.  It  i-  then  cut  into  square 
tlako.  generally  coated  with  graphite, 
and  rinally  it  is  blended.  Various  addi- 
tions have  been  made  at  different  times 
to  make  the  powder  more  stable  or  to 
improve  its  physical  properties.  The 
first  English  patent  mentioned  camphor, 
but  this  was  dropped  on  account  of  its 
volatility  :  diphenvlamine.  aniline  and 
calcium   carbonate  have   also    been  used 

much  for  this  purpose.  The  powder  generally  contains  4o  to  50  per  cent, 
of  collodion  cotton  and  50  to  oil  per  cent,  of  nitro-glycerine.  It  has.  the 
advantage  that  the  plant  required  for  its  production  is  comparatively  simple, 
but  it  causes  very  severe  erosion  in  the  gun-. 

Ballistite  was  adopted  by  the  Italian  Government  soon  after  its  invention, 
but  instead  of  using  it  in  flake  form  it  was  drawn  out  into  cords  with  the  aid 
of  a  solvent,  and  hence  was  given  the  name  "  Filite."  Italian  ballistite 
generally  consists  of  equal  parts  of  nitro-glycerine  and  collodion  cotton,  together 
with  0-5  to  1  per  cent,  aniline  or  diphenvlamine  ;  for  micro-photos  see  Paterno 
and  Traetta-Mosca,  8.8.,  1910,  p.  14.".. 

In  consequence  of  the  severe  erosion  that  ballistite  causes  in  the  gun.  the 
Italians  reduced  the  percentage  of  nitro-glycerine  to  33  per  cent.     It  then 

line  necessary  to  use  acetone  to  assist  the  gelatinization.  and  the  presence 
of  this  solvent  made  it  possible  to  use  a  nitro-cellulose  only  partly  soluble 
in  nitroglycerine  or  ether-alcohol.  From  i  to  3  per  cent,  of  a  light-coloured 
mineral  jelly  was  also  inserted,  so  that  the  powder,  which  is  called  Solenite. 
does  not  differ  very  much  from  Cordite.  The  nitro-cotton  used  contains 
12-4  to  12  -6  per  cent.  X.  and  about  50  per  cent,  of  it  is  soluble  in  ether-alcohol. 
It  is  pressed  into  tubes,  which  arc  out  into  short  Lengths.     The  grains  thus 


Eng.  Pat,   10,376  of  1889. 


SLOW-BURNING  SMOKELESS    POWDERS  303 

obtained  are  translucent  and  of  a  light  brown  colour,  and  look  somewhat 

like  glass  beet  Is. 

^  The  Germans  adopted  ballistite  for  their  navy  in  1898  under  the  name  German 
W.P.C  /89  :  it  had  the  same  composition  as  the  Italian  Filite,  but  was  made  powders- 
up  in  the  form  of  square  flakes  or  cubes.  W.P.  stands  for  Wiirfelpulver, 
i.e.  cube  powder;  In  1897  and  1900  other  powders  were  introduced  less 
erosive  to  the  guns.  These  are  blackish-grey  in  colour,  and  in  composition 
they  appear  to  be  much  the  same  as  Solenite  or  Cordite  M.D.,  except  that  a 
little  diphenylamine  is  added  as  a  stabilizer  as  well  as  mineral  jelly.  The 
powders  are  made  in  tubular  form  and  are  called  R.P.C/97  and  R.P.C/00. 
R.P.  stands  for  Rohrenpulver,  i.e.  tube  powder.  The  Germans  use  nitro- 
glycerine powder  for  their  large  naval  guns  and  for  their  howitzers,  as  they 
consider  that  they  give  more  regular  ballistics  in  these  weapons  than 
nitro-cellulose  powders.  For  their  small-arms  and  77  mm.  field  guns,  etc., 
they  use  nitro-cellulose  powder  of  comparatively  high  nitration  containing 
diphenylamine  as  a  stabilizer,  and  sometimes  some  camphor  as  an  auxiliary 
gelatinizing  agent,  The  powder  for  field  guns  is  made  in  the  form  of  tubes. 
They  have  also  introduced  a  progressive  powder  with  the  surface  gelatinized 
by  means  of  Centralite.1 

The  following  particulars  as  to  German  military  powders  are  given  by 
Berlin  :  2 

N itro-cellulose  powders.     Colour  greyish  yellow  or  brown,  resembling  glue. 
S.P.     Flake  powder  for  rifle  98  and  carbine  98. 
Pl.P.P.  (Platzpatronen-pulver).     Blank  powder  for  same  weapons. 
Gesch.Bl.P.  (Gesehutz-Blattchenpidver).     Flake  powder  for  the  9  cm.  guns  73,  73/88, 

and  the  heavy  12  cm.  gun. 
Gesch.Bl.P.  03         | Powders  made  by  re-working  Gesch-Bl.P.  and  Gr.Bl.P.  to  make 
Gesch.Bl.P.   (umg.)j      them  milder  and  more  stable. 
Gr.Bl.P.  03  (Grobes  Blattchenpulver).     Large  flake  powder  for  use  in  the  15  cm.  ring 

cannon  and   21  cm.  do. 
Gr.Bl.P.  (umg.).     Made  by  re-working  the  above. 
R.G.  961™  _    .  -  . 

R.P.  05)  Iubular  powders  for  use  in  the  field  gun  96  n/a  (127  mm.  long). 

R.P.  97  and  99  (Rohrenpulver).     For  use  in  the  various  10  cm.  guns  (380  mm.  lone) 

R.P.  07.     For  the   13  cm.  gun. 

Man.R.P.   (Manover-Ringpulver).      Blank  ring  powder  for  field  guns. 
NUro-glycerine  powders.     Colour  black,  due  to  coating  of  graphite. 

W.P.  (1)  (Wiirfelpulver).     Cubic  powder,  edge  of  cubes  i  mm.  for  the  3-7  revolver- 
cannon. 

W.P.  (2  X  2  X  f).     For  the  5  cm.  gun. 

W.P.  (4X4X1).     For  the  light  field  howitzer. 

W.P.  (2).     For  the  heavy  field  howitzer  and  21  cm.  bronze  mortar. 

W.P.  (10  X  10  x  i£).     For  the  heavy  field  howitzer  02,  and  15  cm.  howitzer,  and  the 
21  em.  bronze  mortar. 


1  Buisson,  Problem*  des  Poudres,  p.  71.  2  Handbuch  der  Waffenlehre. 


304  EXPLOSIVES 

W.P.  (\-2        12       \'2).     For  the  21  cm.  mortar. 
Rg.P.     Ringpulver).     Short  tubular  powder  for  mortars. 

Man. St. P.    (Manover-Sternpulver).     A    porous    powder   easily    ignited,   made   in   the 
i  of  stars,  colour  grey  with  yellow  Bpote,  for  blank  cartridges  for  manoeu 

About  the  time  of  the  discovery  of  Poudre  B,  the  English  Government 
appointed  a  committee  to  investigate  and  report  upon  the  subject  of  a  suitable 
smokeless  powder  for  the  British  service.  Samples  were  obtained  of  ballistite 
and  all  other  available  powders,  but  the  committee  was  not  satisfied  with 
any  of  them,  and  finally  devised  a  new  one,  to  which  the  name  Cordite  was 
given  from  the  fact  that  it  was  made  in  the  form  of  cord-.  The  composition 
differed  from  that  of  ballistite  in  that  gun-cotton  was  used,  insoluble  in 
ether-alcohol,  and  this  was  incorporated  with  nitro-glycerine  by  means 
of  acetone,  which  was  afterwards  evaporated  off.  Mineral  jelly,  a  semi-solid 
petroleum  product,  was  added  with  the  idea  of  lubricating  the  barrel.  It 
does  not  have  this  effect,  as  it  is.  of  course,  entirely  consumed  in  the  explosion, 
but  it  was  a  most  fortunate  addition,  as  it  exercises  two  most  important 
functions  in  the  powder.  Firstly  it  diminishes  the  temperature  of  the  explosion 
and  bo  reduces  the  amount  of  erosion  of  the  barrel.  At  the  same  time  it 
increases  the  volume  of  gas  given  off  and  so  does  not  reduce  the  power  of 
the  powder  to  any  great  extent.  Secondly,  it  absorbs  the  nitrous  Lra-t-  which 
are  gradually  given  off  when  the  powder  i-  stored,  and  so  prevents  them 
from  increasing  the  rate  at  which  the  powder  decomposes  ;  in  this  May  the 
mineral  jelly  adds  greatly  to  the  chemical  stability  of  the  powder.  It  also 
prevents  the  access  of  the  air  to  the  gun-cotton  and  nitro-glycerine.  and  bo 
reduces  the  amount  of  deterioration  due  to  oxidation. 

The  experimental  work  in  connexion  with  the  invention  of  cordite  was 
mainly  carried  out  in  Sir  F.  Abel's  laboratory  in  Woolwich  Arsenal,  much 
of  the  mo>t  important  work  being  done  by  Dr.  W.  Kellner.  who  afterwards 
succeeded  Abel  as  War  Department  Chemist.  Patent-  No.  5614  of  April 
2.  1889,  and  No.  11,664  of  July  22.  1889,  were  taken  out  on  behalf  of  the 
Government  by  Sir  F.  Abel  and  Professor  (now  Sir)  .T.  Dewar,  who  were 
members  of  the  committee,  and  the  same  year  the  manufacture  of  cordite 
was  commenced  at  the  Royal  Gunpowder  Factory,  Waltham  Abbey. 

Cordite  must  be  considered  one  of  the  most  successful  smokeless  powders, 
t , , i  after  a  quarter  of  a  century,  during  which  it  has  been  subjected  to  far 
more  drastic  treatment  in  all  parte  of  the  British  Empire  than  the  powder 
of  any  other  Power,  it  i-  -till  giving  satisfaction.  The  Germans  meantime 
have  adopted  and  abandoned  a  number  of  different  powders,  and  for  their 
naval  guns  have  finally  decided  upon  a  powder  of  the  same  type  as  cordite. 
The  tw«>  worsl  defects  of  cordite  are  that  it  erodes  the  loius  badly,  especially 
those  of  large  calibre,  and  that  when  Btored  at  a  high  temperature  its  life 
is  a  limited  our.      The  erosion  is  not  bo  Bevere  a-  that  caused  by  the  use  of 


Mk.I. 

M.I) 

37 

(55 

58 

30 

5 

5 

SLOW-BURNING   SMOKELESS   POWDERS  305 

ballistite.  because  the  mineral  jelly  reduces  the  temperature  of  the  gases 
considerably.  Nevertheless,  the  wear  of  the  guns  was  so  bad  in  the  South 
African  War  that  afterwards  the  composition  was  modified  in  order  to  reduce 
the  temperature  further.  The  proportion  of  gun-cotton  in  the  powder  was 
increased,  and  the  explosive  thus  altered  was  given  the  name  Cordite  M.D. 
[i.e.  modified). 

Gun-cotton     ..... 
Nitroglycerine  .... 

Mineral  jelly  ..... 

As  regards  the  chemical  stability  it  is  not  possible  to  say  whether  there  is 
any  other  powder  which  would  be  more  satisfactory,  as  no  other  one  has  been 
subjected  to  adverse  climatic  conditions  in  such  immense  quantities.  It  i>. 
however,  certain  that  all  foreign  Powers  find  it  necessary  to  exercise  constant 
vigilance  over  their  smokeless  powder,  especially  if  it  has  to  be  stored  at  a 
high  temperature  ;  if  the  vigilance  be  relaxed,  catastrophes  inevitably  follow 
sooner  or  later. 

A  large  production  of  the  cordite  for  the  British  services  is  made  in  the 
Royal  Gunpowder  Factory  at  Walt  ham  Abbey,  and  it  was  there  that  the 
methods  of  manufacture  were  worked  out.  Under  the  superintendence  of 
Colonel  Sir  F.  L.  Nathan.  R.A.,  a  great  many  improvements  were  effected 
in  every  part  of  the  manufacture,  whereby  the  safety  of  the  workmen  was 
increased,  the  stability  of  the  explosives  was  improved,  and  the  cost  of 
production  was  reduced.  Many  of  these  methods  have  now  been  adopted  by 
the  private  contractors,  who  also  supply  cordite  to  the  Government. 

When  the  stove,  in  which  the  gun-cotton  has  been  dried,  is  quite  cool,  Weighing  t 
the  men  go  and  unload  it.  The  gun-cotton  is  weighed  out  in  the  porch  of 
the  stove.  These  operations  require  to  be  carried  out  with  the  greatest  care. 
as  dry  gun-cotton  is  very  sensitive.  The  men  wear  nothing  on  their  feet 
but  socks  ;  formerly,  the  gun-cotton  was  weighed  out  into  brass-lined  wooden 
boxes,  but  now  waterproof  india-rubber  bags  are  used.  Several  explosions 
have  been  ascribed  to  the  jar  or  friction  of  the  edges  and  corners  of  such 
heavy  boxes  one  against  the  other,  especially  when  the  boxes  have  contained 
nitro-glycerine.  Such  accidents  can  be  guarded  against  to  some  extent  by 
covering  the  edges  with  rubber  or  leather,  but  it  is  1  tetter  to  avoid  this  danger 
by  using  rubber  bags  ;  but  if  nitro-glycerine  is  to  be  poured  into  them  it 
is  <  ssential  that  they  should  be  absolutely  water-tight,  and  they  should  be 
inspected  frequently  to  ensure  this.  The  scales  are  of  such  a  design  as  to 
reduce  friction  between  the  knife-edges  to  a  minimum  :  the  weights  are  either 
attached  to  the  scale  so  as  to  form  an  integral  pari  of  it.  or  they  are  made 
of  gutta-percha  bottles  filled  with  the  requisite  quantity  of  had  shot.  The 
quantity  weighed  out  into  each  bag  is  that  which  is  required  for  a  charge  of 

VOL.    I. 


306 


EXPLOSIVES 


the  incorporator,  or  if  this  be  of  greal  size,  an  integral  fraction  of  it.  The 
necks  of  the  bags  are  tied  up.  and  tliev  are  transported  by  boat  or  trolley 
to  the  mixing  house. 

Formerly  the  nitro-glycerine  was  weighed  out  into  india-rubber  buckets 
and  then  poured  on  to  the  gun-COtton  iu  the  brass-lined  boxes.  Now.  however, 
it  i-  measured  out  in  a  special  burette  made  of  lead,  which  holds  the  exact 
quantity  required,  and  is  fixed  to  the  floor.  It  is  a  small  cylindrical  vessel 
with  a  conical  top  ending  in  a  narrow  neck  ;  the  bottom  slopes  down  to  one 
side  where  there  is  an  orifice  to  which  a  rubber  tube  is  attached,  the  other 
end  of  which  can  be  passed  over  a  lead  plug  near  the  top  of  the  burette,  when 
it  is  not  being  emptied.  Round  the  outside  of  the  neck  is  a  channel  to  catch 
tiitro-glycerine  that  overflows,  and  this  is  conducted  by  a  pipe  into  a  rubber 
bucket,  so  that  it  can  be  returned  to  the  filter-tank.  The  burette  is  filled 
by  means  of  the  rubber  pipe  attached  to  the  filter-tank,  until  it  is  quite  full, 
and  then  the  burette  is  emptied  by  means  of  the  similar  rubber  tube  attached 
to  it  into  one  of  the  rubber  bags  containing  dry  gun-cotton. 

The  next  operation  is  to  mix  the  gun-cotton  and  nitro-glycerine  roughly 
her.  and  reduce  the  large  primers  of  the  former  to  the  form  of  powder. 
At  one  time  this  was  done  by  rubbing  the  material  through  a  |-inch  copper 
wire  sieve,  but  now  a  special  lead  table  is  made  for  the  purpose.  This  is 
pear-shaped  and  slightly  dished  out.  At  one  end  are  a  number  of  J-inch 
holes,  and  underneath  is  a  sort  of  neck  on  to  which  a  bag  can  be  attached. 
The  contents  of  a  bag  of  gun-cotton  and  nitro-glycerine  are  placed  on  the 
other  and  larger  part  of  the  table  ;  then  a  man  wearing  leather  gloves  transfers 
a  little  at  a  time  to  the  end  where  the  holes  are  and  rubs  it  through  into  the 
bag  below.     No  unnecessary  violence  must  be  used. 

The  "cordite  paste"  thus  obtained  is  next  taken  to  the  incorporating 
house.  The  interior  of  the  incorporator  (see  Figs.  56,  57)  is  thoroughly 
moistened  with  acetone,  the  charge  of  paste  is  added  and  the  rest  of  the 
acetone,  and  the  machine  is  run  for  three  and  a  half  hours,  then  the  mineral 
jelly  is  added  and  the  kneading  is  continued  for  another  three  and  a  half 
hours.  The  quantity  of  acetone  used  is  about  56  per  cent,  of  the  weight  of 
i  he  gun-cotton. 

The  cordite  dough  thus  obtained  is  next  pressed  through  a  die.  which 
forms  it  into  a  cord.  The  type  of  press  used  depends  upon  the  size  of  cordite 
that  is  to  be  made.  The  smaller  sizes,  such  as  3|  which  is  used  for  rifles,  are 
pressed  in  a  small  press  with  only  a  single  orifice,  and  the  cord  as  it  emerges 
is  wound  on  to  a  small  drum,  which  is  then  taken  to  the  cordite  stove  for 
drying.  The  larger  sizes  are  made  in  large  presses  which  have  several  orifices, 
and  the  large  cords  a-  they  emerge  are  cut  by  hand  to  the  lengths  required, 
according  to  the  size  of  the  cartridges  to  be  made  ;  these  sticks  are  then  laid 
upon  trays,   which  are  conveyed  to  the  stove.     Inside  the  press  cylinder 


SLOW-BURNING  SMOKELESS   POWDERS  307 

above  the  die  is  placed  a  piece  of  fine  wire  gauze,  through  which  the  dough 
is  made  to  pass  in  order  to  remove  from  it  all  foreign  material  as  far  as  possible. 
The  dough  is  rammed  into  the  press  cylinder  by  means  of  a  wooden  rammer. 
There  is  only  one  pressing  operation,  whereas  the  American  multiperf orated 
nitro-cellulose  powder  undergoes  four. 

For  pressing  cordite  in  the  ordinary  round  form  the  die  has,  of  course, 
a  simple  round  hole.  For  making  tubular  cordite  a  pin  is  inserted  in  the 
centre  of  the  hole.  In  the  case  of  tubular  cordite  of  small  size  it  is  found 
that  the  tubes  have  a  tendency  to  collapse  in  consequence  of  the  difficulty 
the  air  has  to  pass  through  a  great  length  of  narrow  tube.  To  overcome 
this  difficulty  Lloyd  and  Curtis's  and  Harvey  Ltd.  use  a  perforated  pin 
communicating  through  the  side  of  the  die  with  the  open  air.1 

Occasionally  the  cordite  ignites  as  it  emerges  from  the  press.  As  a  rule 
no  serious  damage  is  done,  but  on  September  17,  1909,  an  ignition  took  place 
at  Waltham  Abbey  whilst  pressing  cordite  Mk.I  size  20,  which  wrecked  the 
press  and  damaged  the  building.  Two  men  were  injured  by  broken  glass 
from  the  windows,  which  were  shattered.  The  fire  was  accompanied  by  two 
explosions  probably  of  acetone  vapour  as  well  as  some  cordite.  The  first 
apparently  destroyed  the  die  seating  and  released  the  die  ;  the  burning  then 
continued,  and  the  second  explosion  occurred  in  the  cylinder.2 

The  cordite  stove  consists  merely  of  a  building  provided  with  suitable  Drying, 
racks  and  heated  by  means  of  steam  pipes  to  a  moderate  temperature,  which 
depends  upon  the  sort  of  cordite  that  is  to  be  dried.  Cordite  Mk.I  size  3§ 
gives  off  its  moisture  so  readily  that  artificial  heat  is  not  necessarj^  in  the 
summer  time.  All  that  is  required  is  to  keep  the  reels  in  the  stove  at  a 
temperature  of  about  15°  C.  for  a  few  days.  The  larger  sizes  are  dried  at 
temperatures  from  38°  to  43°  C.  for  periods  ranging  up  to  a  fortnight.  Cordite 
M.D.  gives  off  its  moisture  much  less  readily  than  Mk.I,  and  consequently 
requires  to  be  kept  in  the  stove  several  times  as  long  ;  in  the  case  of  the  largest 
sizes  the  stoving  occupies  months,  and  is  one  of  the  greatest  difficulties  that 
have  to  be  contended  with  in  the  manufacture.  The  moisture  in  the 
cordite  Mk.I  must  not  exceed  0-4  to  0-6  per  cent,  according  to  size,  but  the 
percentage  allowed  in  M.D.  is  considerably  more.  The  size  of  cordite  is  given 
by  a  figure,  which  is  the  approximate  diameter  in  hundredths  of  an  inch  of 
the  die  through  which  the  cordite  has  been  j^ressed.  Thus  cordite  size  50  has 
been  pressed  through  a  die  about  h  inch  in  diameter.  The  thickness  of  the 
cord  is,  however,  somewhat  less  than  this,  as  it  shrinks  considerably  in  drying. 
Various  particulars  about  the  different  sizes  of  cordite  will  be  found  in  the 
Treatise  on  Service  Explosives,  Appendices  V  and  VI. 

It  is  usual  now  to  recover  as  much  as  possible  of  the  acetone  that  is  given 
off  during  the  drying.     The  cordite  should  therefore  be  placed  in  an  air-tight 

i  Eng,  Pat,  27,700  of  November  28,   1910,  2  See  A.  R.,    L909,  p.   33, 


308 


EXPLOSIVES 


;4.ulc  as  soon  as  possible  after  pressiiig,  and  this  should  be  taken  to  the 
stove  without  unnecessary  lo-^  of  time. 

The  Japanese  Government  formerly  boughl  cordite  for  it-  naval  ordnance 
from  private  firms  in  England,  l>ut  after  the  spontaneous  ignition  on  the 
Mihaaa  in  1905  it  resolved  to  make  it-  own  powder.1  Powders  for  field  and 
mountain  guns  captured  by  the  Russians  during  the  Russo-Japanese  war 
were  found  to  be  aitro-cellulose  powder-  with  4u  to  47  per  cent,  soluble  in 
ether-alcohol  and  12*5  per  cent.  N.1  They  were  in  strip  and  Make  form 
respectively.  The  Japanese  are  said  now  to  be  nitrating  wood  cellulose 
obtained  from  the  island  of  Sakhaline.* 

The  smokeless  powders  used  for  sporting  rifles  are  practically  the  same 
a-  those  used  for  military  small-arms.  Ballistite  of  a  suitable  size  i-  emplt 
to  a  considerable  extent,  as  the  erosion  is  not  so  very  severe  in  these  weapons. 
( lordite  is  very  largely  used  :  most  of  the  principal  explosives  manufacture]-  in 
England  make  cordite  for  the  Government,  and  consequently  have  all  the  plant 
and  experience  required.     Several  slight  modifications  of  cordite  are  also  made. 

Thus  Kvnoch  Ltd.  in  axite  have  replaced  a  portion  of  the  gun-cotton  by 
means  of  potassium  nitrate  or  oxalates  of  potassium  and  barium.  A  sample 
that  I  examined  some  years  ago  had  the  following  composition  : 

Nitroglycerine         ....... 

Gun-cotton     ........ 

Mineral  jelly  and  oil       .....  . 

Volatile   matter        ....... 

Potassium  nitrate  ....... 

in,,. o 

It  was  made  in  the  form  of  flat  strip-.  The  patent-.  Nbs.  12,892  of  June  22. 
L905,  15,564,  1"».  •"■><'>.->  and  1">.566  of  July  lit;.  L905,  cover  the  use  of  olive-oil 
in  addition  to  vaseline  or  mineral  jelly,  of  flakes  and  strips  with  various  forms 
of  ribs  and  knob-  to  facilitate  ignition,  and  the  addition  of  carbonates.  Axite 
i-  al-o  sometimes  made  of  a  composition  resembling  that  of  cordite  MkJ  with 
part  of  the  gun-cotton  replaced  by  potassium  nitrate.  It  i-  claimed  that 
axite  erodes  the  rifle  Less  than  cordite,  as  the  temperature  of  explosion  is 
lower,  and  that  it  does  not  cause  the  barrel  to  rusl  so  much,  because  the 
residue  remaining  in  the  bore  i-  alkaline. 

Eley  Bros,  also  manufacture  a  variety  of  cordite  which  they  call  Mbddite. 
A  sample,  which  I  examined,  had  the  composition: 


29  7 

per 

cent 

631 

, 

.VI 

, 

0-2 

, 

l-'.i 

' 

Nitro-glycerine 
Nfitro-oelluloee 
Mineral  jelly. 
Volatile  matter 


- 
t  :; 
0  2 


per  oent. 


■  in  ProbUnu   dfx  1'onfin  •«.  p.    1T."». 


SJ3.,    L906,  p.  69. 


SLOW-BURNING  SMOKELESS   POWDERS  309 

Of  the  nit ro- cellulose  34-5  per  cent,  was  soluble  in  ether-alcohol.     It  was 
made  in  the  form  of  strip. 

Nitro-cellulose  powders  are  also  used  in  sporting  rifles.  They  are  general] y 
made  of  soluble  nitro-cellulose  containing  12  to  12-5  per  cent,  N  gelatinized 
with  ether-alcohol.  Sometimes  a  few  per  cent,  of  some  other  constituent, 
such  as  resin,  is  added.     Usually  the  powders  are  made  in  the  form  of  flakes' 


CHAPTER   XXII 
REQUIREMENTS   OF  A  SLOW-BURNING  SMOKELESS  POWDER 

Rate  of  burning  :    Form  of  powder  :    Progressive  powder  :    Erosion  :    Nitro- 
glycerine v.  nitro-cellulose  powders  ;     Backflaah  :    Muzzle  flame  :    Products  of 
explosion  :    Testing  propellants  :    Efficiency. 

It  is  required  of  a  powder  for  rifles  or  ordnance  that  it  shall  give  a  high-muzzle 
velocity  with  moderate  pressures,  that  it  shall  not  cause  too  much  erosion 
of  the  bore,  and  that  the  ballistics  shall  be  regular,  i.e.  different  rounds  fired 
with  similar  ammunition  must  give  practically  the  same  velocity  to  the 
projectile.  The  speed  acquired  by  the  bullet  or  shell  is  due  to  the  pressure 
of  the  powder  gases  on  its  base,  as  it  travels  down  the  bore  of  the  fire-arm. 
and  it  is  important  that  the  powder  shall  burn  in  such  a  maimer  that  the 
pressure  is  suitable  during  the  whole  of  the  time  until  the  projectile  leaves  the 
muzzle.  Two  of  the  most  important  facts  in  connexion  with  the  study  of 
interna]  ballistics  are  :  (a)  That  the  grains  of  completely  gelatinized  powders 
burn  away  uniformly  from  the  surface,  so  that  they  retain  their  original  shape. 
but  get  thinner  until  entirely  consumed  ;  and  (b)  that  the  rate  of  burning 
varies  directly  with  the  pressure.  From  the  results  of  experiments  in  closed 
vessels  Vieille  deduced  that  the  rate  of  burning  v  could  be  calculated  from  an 
equation  of  the  form  v  =  cpx,  where  p  is  the  pressure  and  c  and  x  are  constants. 
For  ordinary  black  powder  x  — =  0-f>,  for  highly  compressed  black  prism  powder 
033,  for  brown  prism  powder  0-25,  for  Poudre  B  0-67,  and  for  powder  con- 
taining 50  per  cent,  nitro-glycerine  0-55. a  Mansell  -  and  Petavel8  prefer  an 
equation  of  the  form  v  =  a0  -\-ap,  where  a0  is  the  rate  of  burning  when  t  here 
is  no  pressure,  and  a  is  the  rate  of  increase  of  burning  per  unit  of  pressure. 
For  cordite  a0  =  0-5  cm.  per  sec.  and  a  =  0-018  cm.  per  sec.  per  atmosphere. 
That  the  burning  proceeds  uniformly  by  layers  is  shown  by  the  fact  thai 
if  a  gelatinized  powder  be  fired  from  a  gun,  which  is  too  short  to  allow  of  the 
total  consumption  of  the  explosive,  the  remains  of  the  grains  thrown  from 
the  muzzle  are  found  to  be  in  every  way  similar  to  the  original  grains,  except 
that  the  dimensions  are  reduced. 

1   Vermin,   Poudres  et  Explosifs,  p.  72.  a  Phil.  Trans.,   1907,  207a,  p.  243. 

3  Proc.   U.S.,  79a,  p.  277;    S.S.,   1908,  p.    L66. 

310 


Fio.  61.     Projectile  and  Powder  Charge  for  American  16-inch  Gun 
Weight  of  Charge,  666-5  lb.  nitro-cellulose  powder 

(From  Smithsonian   Report,   1914,  p.  256) 


311 


312 


EXPD»MVK- 


The  result  of  this  is  that  with  a  powder  made  in  the  form  of  cords  or  cubes 
there  is  a  diminution  of  the  burning  surface  a-  the  combustion  of  the  charge 
proceeds,  and  consequently  the  pressure  falls  off  rapidly  as  the  projectile 
approaches  the  muzzle,  although  not  so  much  a-  was  the  case  with  black 
powder,  which  being  porous  did  not  burn  entirely  by  parallel  surfaces.  In 
<>r«ler  to  overcome  this  objection  other  forms  are  often  adopted  for  the  grains 
of  powder.  If  a  strip  or  Make  be  used,  the  width  of  which  i-  great  compared 
with  the  thickness,  the  area  of  surface  remains  practical!  H  <nt  until  the 

material  i-  entirely  consumed.  It  has  been  found,  however,  that  powders 
made  up  in  these  rlat  form-  are  liable  to  iiivi.-  irregular  ballistics,  and  this  has 
been  ascribed  to  the  obstacles  in  the  way  of  regular  ignition,  when  two  grain- 
lie  flat  against  one  another.  -  S  h  have  proposed  to  remedy  this 
defect  by  providing  the  strips  or  flake  >  with  ribs  or  knobs. 

instancy  of  the  area  of  surface  can  also  be  attained  by  making  the  powder 
in  the  form  of  tubes.  There  is  then  no  difficulty  about  the  ignition,  but 
the  pressure  inside  the  tul>e  i>  always  somewhat  greater  than  outside,  because 

_  -    ipe  very  readily,  and  this  sure  may  become 

sufficiently  great  to  >plit  the  tubes.  If  this  occur,  the  ballistics  become 
unreliable,  partly  on  account  of  the  sudden  relief  of  pressure,  and  partly  be- 
cause the  surface  i-  increased  in  an  erratic  manner.  If  the  gravimetric  density 
of  the  powder  in  the  chamber  be  high,  the  general  pressure  is  inere-a-ed.and  the 
different  en  the  pressure  inside  and  outside  the  tubes  is  diminished. 

If  instead  of  only  one  perforation  there  be  several  as  is  the  case  with  tin- 
American   multiperforated   powder,   the   pressure   increases   as   the   burning 
a,  and  consequently  the  pressure  is  maintained  at  a  higher  level  whilst 
the  projectile  i-  travelling  through  the  forward  portion  of  the  bore.    Thi-  Bhould 
•   be  carried  too  far.  because  it  is  not  practicable  to  have  great  thickness 
of  metal  near  the  muzzle.     To  prevent  the  grains  splitting  in  consequence  of 
great  pressure  inside  them  they  are  cut  into  short  lengths. 

The  thickness  or  diameter  of  a  powder  -In  uld  be  such  that  it  is  entirely 
uned  shortly  before  the  projectile  reaches  the  muzzle. 

The  relative  rate  of  burning  of  the  powder  charge  at  different  instants 
can  also  be  regulited  by  submitting  the  explosive  to  an  operation,  wh< 
the  surface  layer  of  the  material  i-  modified.     Such  "progressive'5  powdei 
•    R   ttweil  by  treating  the  grains  of  nitro-celluli  -  der  with 

an  alcoholic  solution  of  '"  Centralite  "  (dimethyl-phenyl-urea)  ;  this  causes  the 
outer  layer-  of  the  grains  to  burn  more  -lowly,  and  so  causes  the  chamber 
to  be  1»  as,  and  that  further  down  the  bore  to  be  higher.  The  same 
method  i-  In-ini:  tried  in  Prance.1  Another  method  i-  to  treat  the  powder  m 
a  drum  with  a  solution  of  O'l  to  1  percent,  of  paraffin-wax  dissolved  in  benzole. 
Flake  powder-   for  -mall-arm-  are   sometimes   coated   with   graphite.     This 

•    Flon-ntin,  >.>..    1913,  p.  32 ;    also  .  p.   4<». 


fc 


o     in 

o 


a. 


C 


ft5 

s 
e 


g 
o 


313 


314  EXPLOSIVES 

not  only  restrains  the  initial  velocity  of  ignition  but     too  facilitates  the  Loading 
from  loading  mach: 
y  ....... ,  i..  There  has  been  considerable  as  i<>  tin-  relative  advantages  and 

ine    r.  wMtt  disadvanl   ges    E  niteo-eeflnlose  and  nitro-glycerine  powders.     The  advantages 
2^      pow-  c}ajnit.(}  f,,,.  ,  ere  are  that  they  give  more  regular  ballisl 

do  _        back-flash  when  fired,  are  more  powerful,  are  cheaper  to  manu- 

facture, leave  L  ie  in  the  gun.  and  have  at   least      -   good  chemical 

stability  as  nitro-eellulose  powders.     Their  great   disadvanf    _  that!   the 

temperature  of  explosion  i-  high,  and  consequently  thi  .  of  the  b<  re 

:  •  •  •    gun  is  very  aevere. 

;>ite  of  the  fact  that  they  erode  the  guns  more,  most  of  the  Powers 
glycerine  powders  in  their  Large  guns,  and  the  principal  reason  for 
this  is  that  they  give  m  _  ilar  ballistics.     It  i-  impossible  to  drive  tin- 

whole  of  the  solvent  out  of  a  colloided  nitro-eelluL 

the  drying  he  greatly  prolonged,  and  indeed  it  i-  advisable  to  leave  several 
•    iii  the  powder,  because  otherwise  it  i>  too  brittle.     But  this  residual 
solvent  if  inty.  because  it  gradually  diffuses  from  the  centre 

of  the  grains  or  stripe  ind  evaporates,  even  though  the  powdei 

in  cl   -  eptacles,     The  lo->  of  this  combustible  matter  makes  the  powder 

moi  .ful.  but  what  is  more  serious  is  that  th*-  material  becomes  harder 

and  more  brittle,  and  it  may  break  up  when  fired,  and  consequently  give  Iijl'Ii 
press  .nd  irregular  velociti 

tddition  of  a  considerable  proportion  of  nitro-glycerine  to  a  jm  wder 
mak-  a        give  up  it>  volatile  matter  much  more  readily.     Apparently  the 

-  -  Erom  the  particles  of  gun-cotton  to  the  adjacent 

of  nitro-glycerine,  and  diffuses  through  the  latter  t<>  the  outside  «  f  the  stick 

or  Hake  much  more  rapidly  than  it  can  through  the  colloidal  nitro-cellulose  ' 

.It  is  that  the  percentage  of  volatile  matter  can  be  reduced  without 

difficulty  to  1  per  cent,  or  a  little  more,  and  if  a  i<  f  t lii-  afterwards 

uot  alter  tlie  composition  of  the  powdi  r  materially,  and 
the  1<»>-  nf  the  whole  of  it        -      I  affect  the  physical  j •  i « » j  ertu  -  "f  the  material. 
•  of  the  nitro-glycerine  causes  it  to  remain  always  a  tough  or 
_  itJy  plastic  m   as      cording  to  the  percentage.     Nitro-glycerine  ]  owdera 
are  also  considerably  less        _  pic.     Thus  N.   L.  Hansen  found  that   in 

a  nitro-celluloee  powder  in  strip  form  0*78  mm.  thick  freely  exj  oa  d  the  moisture 
varied  fr<>m  1*71       -  ent.  according  to  the  time  of  year  and  the  amount 

of  moisture  in  the  atmosphere,  and  in  a  tubular  nitro-cellulose  powder  3-70 
mm.  thick  from  1-36  percent.'     With  a  nitro-glycerine  powder  the 

1  It  has  been  found  by  H.  Beehhold  and  .T.  Ziegler  that  v.  _■•  Is  diffu- 

is  practically  I  as  in  the  pure  solvent,  in  very  stiff  gels  it  is  much  smaller, 

and  may  be  either  increased  or  diminished  by  the  addition  of  other  substan<  •  -    / 

*  8J3.,   1911,  }..  461. 


REQUIREMENTS  OF  A  SLOW-BURNING  SMOKELESS  POWDER  315 

amounts  of  Mater  absorbed  and  the  variations  would  have  been  much  smaller, 
as  the  nitro-glycerine  waterproofs  the  powder. 

The  smaller  bulk  of  nitro-glycerine  powders  is  of  some  advantage  on  board 
ship,  where  magazine  room  is  limited.  The  lighter  weight  of  th  cartridges 
also  makes  them  rather  more  easy  to  handle. 

The  question  of  erosion  wasanvestigated  byVieille,1  who  showed  that  the  tern-  Erosio 
perature  produced  in  the  explosion  was  the  principal  factor.  He  fired  charges 
of  various  explosives  in  vessels,  which  were  closed  except  for  a  small  orifice 
drilled  through  a  metal  ping,  which  was  weighed  before  and  after  the  experiment . 
He  found  that  the  erosion  increased  with  increase  of  length  of  the  orifice,  with 
( lecrease  of  the  diameter,  and  with  increase  of  the  volume  of  gas  and  the  pressure. 
The  influence  of  the  nature  of  the  explosive  is  shown  by  the  following  Table  : 


Explosive 

Pressure 

kg.  /cm.2 

Temperature 

(calculated) 

Erosion 
cub.  mm.  per  g. 

Gunpowder,  75  per  cent,  saltpetre. 

2167 

291U 

2-2 

78 

1958 

3513° 

4  r, 

Nitro-guanidine      .... 

2019 

•to: 

2-3 

Nitrocellulose          .... 

2276 

2676 

ti-4 

Solenite  (34  per  cent.  X/G)    . 

244!) 

— 

13-8 

Dynamite   (75  per  cent.   N/G) 

2084 

31  CI 

180 

Cordite.          ..... 

2500 

— 

181 

Xitro-mannite          .... 

2361 

3429° 

23-6 

Ballistite  (50  per  cent.  N/G). 

244(1 

3384° 

24-3 

Blasting  gelatine    .... 

2458 

:!.->45° 

31 -4 

This  clearly  shows  the  influence  of  the  temperature  of  the  explosion  gases. 
The  lower  the  melting-point  of  the  metal,  the  more  it  is  eroded  ;  the  following 
results  were  obtained  by  filing  charges  of  3*55 grains  of  ballistite.  using  plugs 
of  different   metals  : 


Platinum       .... 

59-1 

Platinum-iridium  . 

74 

Iron      ..... 

68-2 

( lannon  steel 

84-5 

Clirome  steel  (3-5  per  cent.) 

98 

Copper            .... 

98-8 

Nickel   steel    (24   per   cent.) 

107 

Cast  iron       .... 

131 

Silver  ..... 

230-8 

Bronze           .... 

279 

Brass    ..... 

326 

Zinc     ..... 

1018 

cub. 


1  P.  et  8.,  vol.  xi.,   1902,  p.    157. 


:;]<;  EXPLOSIVES 

ft  will  be  seen  that  the  melting-point  affects  the  erosion  far  more  than  the 
hardness  of  the  metal.  Similar  experiments  have  been  carried  out  in  America,1 
where  charges  of  Bmokeless  powder  were  tired  in  an  armour-piercing  shell. 
closed  with  plugs  of  different  metals,  which  were  drilled  with  holes  hot  mm. 

in  diameter.  The  erosion  was  measured  by  the  number  of  times  the  area  of 
the  orifice  was  enlarged  : 

Wrought   iron          .......  4  .">  times 

Martin   steel  ........  4-5  ,, 

3  per  cent,  tungsten  steel       .....  4-5  „ 

Martin  steel  with  3  per  cent,  tungsten    .          .          .  4-7  „ 

3.1  per  cent,  nickel  steel          .....  5-0  „ 

20  per  cut.  nickel  steel          .....  5-9  ,, 

Manganese  bronze.          ......  230  „ 

The  erosion  is  to  be  ascribed  to  the  fusion  of  the  surface  of  the  metal,  which 
is  then  swept  away  by  the  rush  of  gas.  A-  regards  the  influence  of  pressure 
Yieille  found  that  up  to  a  pressure  of  100  kg.  cm.2  the  erosion  was  only  slight  : 
it  increases  very  rapidly  with  rise  of  pressure  from  900  to  2000  kg.  cm.2,  and 
then  remains  practically  constant  from  2000  to  4000  kg. 

Noble  carried  out  an  elaborate  series  of  experiments  with  cordites  specially 
manufactured  with  varying  proportions  of  nitro-glycerine.2  These  were  tested 
in  the  calorimetric  bomb  and  also  fired  from  the  gun.  The  results  are  shown 
in  Fig.  63.  It  will  be  seen  that  when  the  percentage  of  nitro-glycerine  is 
increased  from  in  to  00  per  cent.,  the  quantity  of  heat  increased  •'•<•  per  cent., 
but  the  erosion  was  greater  by  nearly  500  per  cent. 

When  only  small  charges  are  used,  the  erosion  is  not  very  severe,  for 
both  the  temperature  and  pressure  in  the  chamber  are  much  lower.  It  is 
gely  for  this  reason  that  practice  with  large  guns  is  mostly  carried  out 
with  reduced  charges.  It  is  reckoned  that  the  wear  of  the  gun  due  to  a  proof 
round  i-  equal  to  that  of  two  full  charges,  and  that  a  full  charge  of  powder  is 
equivalent  to  four  f-charges  or  sixteen  -A -charges  or  sixteen  blank  chargi  s. 
One  round  of  cordite  Mk.l  is  equivalent  to  Bevera)  of  cordite  .M.D.  producing 
the  same  ballistics.  It  is  in  large  ordnance,  firing  very  heavy  charges  of 
powder  in  order  to  obtain  a  high  muzzle  velocity,  that  the  erosion  is  most 
severe  ;  in  smaller  guns  it  is  comparatively  trifling.  By  properly  proportioning 
the  chamber  and  the  length  of  the  gun.  and  making  the  powder  of  the  right 
size  and  shape,  the  erosion  can  be  reduced  somewhat,  but  naval  guns  of  large 
size  require  re-lining  after  they  have  fired  a  few  hundred  full  charge  - 

With  smokeless  powder  the  erosion  mostly  consists  in  washing  the  surface 

of  the   metal  smoothly  away.     With   high   charges  of  black  powder,   which 

generated  temperatures  of  the  same  order,  the  metal  was  scored  into  deep 

rnt-.  and  this  has  been  ascribed  to  the  m<  chanical  action  of  the  -olid  particles 

1  Set   s.s..   1907,  ,,.  jii.  -  Artillery  <n«l  Explosives,  ]>.  634. 


REQUIREMENTS  OF  A  SLOW-BURNING  SMOKELESS  POWDER  317 

in  the  products  of  explosion.     With  smokeless  powder  there  is  some  scoring, 
but  not  nearly  so  much. 

Erosion  is  most  severe,  not  in  the  powder  chamber,  but  just  in  front  of 
it,  where  the  powder  gases  rush  past  between  the  copper  band  of  the  projectile 


20/'  30^  40/.  507. 

Per  cent.  Nitroglycerine 
Fig.   (53.     Noble's  Erosion  Experiments 

and  the  bore  of  the  gun.  Further  down  the  bore  the  wear  is  much  less,  as 
the  pressures  are  less,  the  copper  bands  lit  the  rifling  better,  and  the  projectile 
is  travelling  so  rapidly,  thai   (lie  escapes  of  gas  have  little  time  to  do  harm. 

The  inner  tubes  of  guns  also  occasionally  split.  This  is  apparently  caused 
by  the  alternate  heating  and  cooling  of  the  inner  surface  of  the  metal  combined 
with  the  compression  to  which  it  is  subjected.  The  result  is  that  the  surface 
layer  <»f  metal  is  in  a  state  of  tension. 

^  ainell  lias  shown  that  just  as  nitro-glycerine  powders  cause  more  erosion 
I  hau  those  that  only  contain  nitro-cellulose,  so  nitro-cellulose  powders  of  high 
nitration  are  worse  in  this  respect  than  those  of  low  nitration,  in  spite  of  the 


60/, 


318 


EXPLOSIVES 


fact  thai  a  smaller  charge  is  required.1  Like  Vieille  he  found  that  the  erosion 
is  practically  independent  of  the  pressure  if  it  exceed  2000  atmospheres. 
Yarnell  also  tried  the  effect  of  adding  considerable  quantities  of  water  or 
paraffin  to  the  charge.  The  erosion  was  greatly  reduced  thereby,  and  the 
pressures  were  increased.  Such  additions  have  been  advocated  frequently,  but 
aparl  from  the  difficulty  of  carrying  them  out  under  war  conditions,  the 
presence  of  cooling  material  in  the  lump,  so  to  speak,  must  render  the  ballistics 
uneven.  Any  addition  should  be  incorporated  with  the  powder  during 
manufacture.  The  mineral  jelly  in  cordite  reduces  the  temperature  of  the 
products  several  hundred  degrees,  and  in  fact  cordite  M.D.  has  a  temperature 
of  explosion,  which  is  but  little  higher  than  that  of  some  nitro-cellulose 
powders.  An  addition  such  as  this  does  not  diminish  the  ballistic  efficiency 
of  the  powder  1<>  any  great  extent,  because  the  reduction  of  temperature  is 
] tartly  compensated  by  the  increase  in  the  volume  of  gas  formed. 

Vieille  (he.  cit.)  showed  the  effect  of  adding  nitro-guanidine  to  powders  : 


Erosion  per  gramme 

Nitro-cellulose 
Powder 

Cordite 

Ballist  it.' 

Alone         ...... 

With  30  per  cent,  nitro-guanidine 
„     50 

6-4 
5-45 

.'Ml 

181 
130 

8-44 

24-3 
14-2 

7-8 

The  difficulty  is  to  find  a  substance  that  can  be  incorporated  with  the  powder 
in  sufficienl  quantity  without  affecting  injuriously  any  of  its  qualities.  Nitro- 
guanidine,  for  instance,  makes  it  brittle.2 

With  a  low  temperature  of  explosion  is  always  associated  a  low  percentage 
of  oxygen  in  the  powder,  and  consequently  a  large  proportion  of  carbon 
monoxide  in  the  products.  When  large  guns  are  fired  the  combustible  powder 
gases  are  liable  to  catch  light  at  the  muzzle  and  burn  down  the  bore,  and 
on  the  breech  being  opened  this  (lame  may  emerge,  especially  if  the  gun  be 
pointing  to  windward.  Tn  France,  where  nitro-cellulose  powder  only  is  used, 
a  number  of  disasters  have  been  caused  by  such  flames  emerging,  and  setting 
light  to  cartridges  in  the  turret,  or  standing  near  the  gun.  Similar  accidents 
have  occurred  in  the  United  States,  where  also  nitro-cellulose  powders  are 
employed  exclusively.  This  danger  is  also  present  with  cordite,  although  not 
to  the  same  extent,  and  must  be  guarded  against. 


1  Journ.  Aim  i.  St>c  Sural  Engineers,  May   1910;    s.s.,  1911,  p.   !!•:{, 

2  Bravetta,  N.N..  1912,  p.  493, 


REQUIREMENTS  OF  A  SLOW-BURNING  SMOKELESS  POWDER  319 

When  cannon  are  fired,  flames  appear  at  the  muzzle  due  to  the  ignition  Muzzle  flami 
of  the  combustible  gaseous  products.  This  is  objectionable,  because  at  night 
it  reveals  the  position  of  the  guns.  The  flame  can  be  diminished  or  even 
abolished  in  some  cases  by  adding  a  few  per  cent,  of  sodium  resinate  or  other 
sodium  or  potassium  salt,1  but  the  quantity  of  smoke  is  thereby  greatly 
increased  and  this  Mill  reveal  the  position  by  day,  and  will  obstruct  the 
gunners. 

Muzzle  flame  is  due  to  high  temperature  of  the  gases  as  they  emerge  from 
the  gun  as  well  as  to  their  composition.  With  a  large  charge  of  powder  it 
is  much  more  difficult  to  keep  this  temperature  below  the  ignition  point  of 
the  gases.  The  problem  of  doing  away  with  it  has  much  in  common  with 
that  of  the  preparation  of  coal  mine  explosives. 

Numerous  analyses  of  the  products  from  the  explosion  of  cordite  and  Products  of 
Rottweil  nitro-cellulose  powder  have  been  published  by  Noble.2  The  powders 
were  exploded  in  a  calorimetric  bomb  at  various  densities  of  loading,  but 
only  the  figures  for  the  lowest  density,  0-05,  are  reproduced  here,  as  they 
probably  represent  most  nearly  the  composition  of  the  gases  evolved  in  the 
gun. 


explosion. 


Cordite 

Cordite 

Rottweil 

Mk.1 

M.D. 

R.R. 

Vol.  permanent  gas,  c.c.  per  g. 

678-0 

781-8 

814-7 

Vol.  total  gas,  c.c.  per  g. 

877-8 

955-4 

993-1 

Composition  of  perm,  gas  : 

co2 

2715 

1815 

17-90 

CO 

34-35 

42-60 

43-45 

H2 

17-50 

2315 

24-40 

t'H4 

•30 

-35 

•CO 

N, 

20-70 

15-75 

13-65 

Composition  of  total  gas  : 

coa 

20-97 

14-85 

14-68 

CO 

26^:; 

34-87 

35-63 

Ho 

13-52 

18!».-» 

20  01 

CH4 

■23 

•29 

■49 

Na  - 

15-99 

12-89 

111!) 

H20 

22  7ii 

1815 

18-00 

Pressure,  tons  8q.  in. 

2-9 

2-7 

:;■;;:. 

Heal   evolved  (water  Liquid)   . 

L272 

L036 

896 

Tempre.  of  explosion,  °  C. 

r>  I :.  I 

4056 

3488 

The  temperatures  were  calculated  with  very  low  values  for  the  specific  heats 
and  are  consequently  high  and  have  only  relative  value. 


1  See  Schildermann,  S.S.,   1913,  p.   126.  2  Proc.  Roy.  Soc,  76a,   1905,  p.  381. 


32(> 


EXPLOSIVES 


Macnab  and  Leighton  carried  oul  Bimilar  experiments  with  cordite.1  The 
relative  temperatures  of  explosion  determined  with  thermocouples  as  compared 
with  the  sporting  powders  given  on  p.  .'527  were  L91  and  L68  for  <  lordite  Mk  I 
and  M.l>.  respectively. 

According  to  Schumacher,2  American  multiperforated  powder  fired  at  a 
density  of  0*05  gives  664-4  c.c.  of  permanenl  gas  per  gramme  having  the 
composition  : 


CO, 
CO 

II: 
til, 

N. 


20-7 

Hid 

I  17 

L-3 

1(1-7 


Sir  A.  Noble  lias  also  given  the  following  figures  in  Engineering  : 


Vol.   Cms 

Heat 

Vol.  x  Heal 
1 000 

(  ordite  MkJ           .... 

875-5 

124(5 

L090 

M.I) 

913-5 

in:}() 

'.Ml 

Ballistite,   [talian  .... 

810-5 

1305 

L057 

Norwegian   107       .... 

999-9 

1005 

905 

Nitrocellulose         .... 

934 

924 

863 

Norwegian   165       .... 

9099 

935 

851 

Blanche  aouvelle   .... 

Sl»L> 

1003 

S24 

Lyddite            ..... 

960-4 

856 

S')-> 

When  a  new  explosive  is  being  investigated  all  the  usual  characteristics 
of  an  explosive  may  with  advantage  be  determined,  such  as  the  power. 
inflammability,  residue,  volume  and  composition  of  gases.  The  recoil  and 
erosion  of  the  gun  may  also  he  measured, and  the  temperature  of  combustion 
calculated.  A  determination  may  also  be  made  of  the  law  of  combustion, 
i.e.  the  rate  of  rise  of  pressure  with  time,  by  means  of  a  spring  manometer/1 

For  current  supplies  of  powder  the  principal  tests  are  :  determination  of 
the  composition  by  chemical  analysis,  stability  tests,  measurements  of  the 
muzzle  velocity  by  means  of  an  electric  chronograph,  and  of  the  maximum 
pressure  in  the  chamber  of  the  gun  by  means  of  a  crusher  gauge.  The  mean 
and   jireatesl    differences  of  series  of   these   last    two  arc  also   taken   into  con 

sideration. 

Of  the  total  energy  of  the  powder  from  I  .*>  to  l<>  per  cent,  is  actually  utilized 
as  kinetic  energy  of  the  projectile.4     Of  the  remainder  the  greater  part  remains 


i  ./.  8oc.  Chem.  /ml.,   1904,  |>.  ::<><». 
:1  Vennin  et  Chesneau,  p.   142  et  seq. 


-  S.S.,   L907,  p.  M. 

1   Ibid.,  ,,.    I  IT. 


REQUIREMENTS  OF  A  SLOW-BTJBNING  SMOKELESS  POWDER  321 

in  the  powder  gases  as  heat  and  kinetic  energy,  but  the  barrel  also  absorbs 
a  considerable  proportion  as  heat.  An  investigation  carried  out  with  the 
German  rifle  M.98S  gave  the  following  distribution:1 


Heating  barrel        .... 

22.3  per  cent 

Bullet,  velocity  energy  . 

.      32-7 

,,        rotation  energy  . 

0-2 

Recoil  ...... 

0-9 

«  ..i-i  -.  cartridge  case 

.      43-7 

100 


1  C.  Cranz  and  R.  Rotho,  S.S.,   1908,  p.  303. 


VOL.  I. 


21 


CHAPTER    XXIII 


FAST-BURNING   SMOKELESS   POWDERS 

Shot-gun  powders  :  Condensed  powders  :  Bulk  powders  :  Ingredients  :  Manu- 
facture of  bulk  powders  :  American  method  :  33-grain  powders  :  30-grain 
powders  :  French  powders  :  German  powders  :  American  powder.-?  :  Austrian 
powders:  Requirements:  T-  -  _  -  t-gun  powders:  Powders  for  trench 
howitzers  :    Blank  powders 

The  shot-gun  is  distinguished  from  the  rifle  not  only  in  not  having  a  rifled 
bore,  but  also  in  being  generally  of  considerably  greater  calibre.  To  produce 
a  weapon  easy  to  handle  it  is  necessary  to  make  the  forward  portion  of  the 
barrel  very  light.,  and  therefore  there  must  be  but  little  pressure  except  near 
the  breech.  The  distribution  of  the  shot  in  a  uniform  maimer,  i.e.  the 
formation   of   a   good   pattern,    seems   to   require   that    comparatively   little 

sure  be  exerted  on  the  shot  in  the  forward  portion  of  the  barrel.     For 
-  a  shot-gun  powder  must  burn  much  more  rapidly  than  a  rifle 
powder,  and  therefore  there  must  be  more  surface  exposed.     These  powders 
are  of  two  kinds  :    the  Si  condensed  "  and  "  bulk  '"  types. 

In  the  condensed  powders  the  nitro-cellulose  is  completely  gelatinized  : 
they  are  made  in  much  the  same  way  as  rifle  powders,  but  are  formed  into 
quite  small  grains  or  very  thin  flake-.  <  annonite.  Shot-gun  Rifleite  and 
Sporting  Ballistite  are  of  this  type,  but  the  first  two  of  these  are  no  longer 
manufactured  ;  their  composition  is  given  in  the  Table  on  p.  327.  Cannonite 
made  in  the  form  of  small  graphited  grains  ;  the  process  of  manufacture 
was  described  by  Sanford  in  the  fir>t  edition  of  his  Niiro-Explosives, 
p.  L82.  Shot-gun  Rifleite  was  in  the  form  of  thin  flakes  ;  Sporting  Balli>tit«- 
i-  also  a  flake  powder.  The  advantages  claimed  for  these  powders  are  that 
they  leave  very  little  ><>Li<l  residue  when  burnt,  and  are  consequently  free  from 
smoke  and  "  blow-back."  and  leave  but  little  folding  in  the  bore,  that  they 
are  not  much  affected  by  exposure  to  moist  air.  are  very  quick  and  give  little 
recoil.  On  the  other  hand,  they  require  special  cartridge  cases  with  a  cone 
of  pasteboard  filling  up  part  of  the  base,  because  otherwise  the  case  would 
not  be  entirely  filled,  and  also  too  much  of  the  powder  would  be  exposed  to 
the  flash  of  the  cap.  In  consequence  of  the  small  space  occupied  by  the 
powder  charge  very  slight  variations  in  the  strength  of  the  cap  and  other 

322 


FAST-BURNING  SMOKELESS   POWDERS  323 

conditions  produce  great  variations  in  the  pressures  generated,  and  the  gun 
may  therefore  be  strained  dangerously,  and  difficulties  are  sometimes 
experienced  in  extracting  the  cartridge  cases.  These  powders  are  also  more 
difficult  to  manufacture  than  those  of  the  bulk  type. 

Bulk  powders  are  so  made  that  the  charge  for  a  12-bore  gun  occupies  Bulk  powd 
the  same  space  in  the  cartridge  as  the  standard  charge  of  82  grains  of  black 
powder  occupying  a  space  of  3  liquid  drams  equal  to  10-65  c.c.  The  first 
successful  smokeless  powder  was  that  of  Captain  E.  Schultze,  of  the  Prussian 
Artillery,  who  made  it  from  nitrated  wood.1  This  was  first  cut  into  thin 
veneers,  from  which  small  cylinders  were  punched,  and  then  it  was  purified  by 
boiling  with  soda,  bleaching  and  washing.  After  nitration  the  nitro-lignin  was 
boiled  with  soda,  and  washed  with  cold  water,  and  afterwards  impregnated 
with  the  nitrates  of  barium  and  potassium.  In  the  course  of  time  various 
modifications  have  been  made  in  the  process  of  manufacture.  The  wood 
fibre  now  used  is  thoroughly  purified  by  drastic  chemical  treatment,  and 
is  formed  into  grains  by  manipulation  with  solvents  after  nitration.  The 
treatment  with  solvent  also  hardens  the  grains  and  makes  them  more  water- 
proof. For  further  information  about  the  early  development  of  Schultze 
powder  see  ante,  p.  47,  also  Guttmann,  Progress,  p.  38  and  Appendices,  and 
Griffith's  Patents  3294  of  1877,  and  11,808  of  1884.  Most  of  the  other  powder 
manufacturers  use  nitro-cotton  instead  of  nitro-lignin,  but  the  Schultze 
Company  have  adhered  to  wood  fibre,  as  they  consider  that  a  powder  made 
with  it  is  less  sensitive  to  variations  of  loading,  and  gives  more  satisfactory 
results  under  adverse  climatic  conditions. 

Bulk  powders  frequently  contain  a  small  proportion  of  substances,  such  as  ingredient 
vaseline  or  paraffin  wax,  which  serve  to  moderate  the  action.  Starch  also  is 
sometimes  used  ;  it  helps  to  hold  the  grains  together.  Camphor  is  somewhat 
objectionable,  as  it  is  volatile  and  escapes  on  long  storage.  The  mono-  and 
dinitro -derivatives  of  benzene  and  toluene  are  present  in  some  powders  ; 
like  camphor  they  have  the  property  of  assisting  the  gelatinization  of  the 
fibres.  Other  materials  that  are  added  sometimes  are  lamp-black,  wood 
meal,  various  gums  and  potassium  ferricyanide.  In  order  to  complete  the 
oxidation  of  such  added  organic  matters,  and  also  to  make  the  rate  of  burning 
more  uniform,  nitrates  of  barium  and  potassium  are  added  :  the  barium 
salt  lias  the  advantage  that  it  produces  comparatively  little  smoke  and  is 
not  hygroscopic.  On  the  other  hand,  it  leaves  a  residue  in  the  gun,  which 
is  difficult  to  remove.  Therefore  it  is  customary  to  use  a  considerable 
percentage  of  barium  nitrate  together  with  a  small  proportion  of  potassium 
nitrate.  A  small  quantity  of  aniline  dye  is  also  added  in  many  cases  to  colour 
the  powder.  Other  powders  are  coated  with  graphite,  which  renders  them 
less  liable  to  become  ignited  by  electrification,  although  there  is  little  danger 

1  $ee  Eng.  Pat.  900  of  1864. 


324  EXPLOSIVES 

of  this  in  powders  that  contain  mineral  salts.  Graphiting  also  retards  the 
ignition  of  the  powder  and  so  acts  as  a  moderating  agent.  The  oitro-cellulose 
used  generally  contains  L2-5  to  12-8  per  cent,  nitrogen,  and  is  partially  Boluble 
in  ether-alcohol.  The  addition  of  calcium  carbonate  improves  the  stability 
of  the  powder  by  neutralizing  any  acid  that  is  given  off,  but  it  should  be 
very  intimately  mixed  with  the  nitro-eelhilose,  and  such  intimate  contact  is 
besl  produced  by  precipitating  the  carbonate  in  the  fibres  by  using  hard 
water  for  the  boiling'of  the'nitro-cellulose. 

The  incorporation  of  the  ingredients  is  in  many  cases  performed  under 
exlge-runnersTsimilar  to'those  used  for  the  milling  of  black  powder.     The  wet 

nitro-cellulose,  containing  some  40  per 
cent,  of  water,  is  roughly  mixed  with  the 
other  ingredients,  and  these  are  ground 
together  in  the  mill,  water  being  added 
from  time  to  time  to  keep  the  mixture 
moist.  The  duration  of  the  milling  and 
the  amount  of  water  are  regulated  accord- 
ing to  the  gravimetric  density  required 
in  the  finished  product.  The  longer  the 
milling  and  the  higher  the  proportion  of 
water,  the  greater  the  gravimetric  density. 
I'n..  lit.     English  Bulk  Powder  The    material   is    then   passed  through  a 

(Thorn,  r,  8.S.,  1907,  p.  424).  sfeve  ^th  meshes    somewhat  larger  than 

the  finished  grain  is  to  be.  The  moist 
grains  thus  formed  are  then  dried  in  a  stove  by  means  of  a  current  of  hot 
air,  the  powder  being  spread  on  trays  to  a  depth  of  not  more  than  ',)  inches. 
When  dry  the  material  should  be  allowed  to  cool  down  in  the  stove  before 
it  is  moved.  The  dust  and  large  lumps  are  then  removed  by  passing  the 
powdei  through  slope  reels. 

The  next  operation  is  the  important  one  of  hardening  the  grain  by  treating 
it  with  solvent.  This  is  frequently  done  by  spraying  it  with  the  solvent 
inside  a  drum,  which  can  be  closed  hermetically  and  rotated  about  its  axis. 
After  a  few  minutes'  rotation  the  grains  are  thoroughly  moist.  The  powder 
is  then  allowed  to  sleep  for  some  time  either  in  the  same  vessel  or  another 
one.  and  then  it  is  dried.  The  preliminary  drying  may  be  carried  out  in  a 
solvent  recovery  plant  consisting  of  a  rotating  drum  provided  with  a  steam 
jacket  and  a  hollow  axle,  which  is  connected  through  a  condensing  coil  with 
a  vacuum  pump.  The  coil,  pump,  etc.,  are  placed  in  a  separate  compartment 
from  the  drying  drum,  which  is  isolated  by  means  of  a  wall  having  no 
openings,  in  order  to  minimize  the  danger  of  fire.  A  considerable  proportion 
of  the  solvent  is  recovered  in  ilns  way,  and  after  redistillation  may  be  used 
again,  but  in  order  to  obtain  a  satisfactory  recovery  it  is  necessary  to  cool  the 


FAST-BURNING  SMOKELESS   POWDERS  325 

coil  by  means  of  refrigerated  brine  to  a  temperature  considerably  below  the 
freezing-point  of  water.  The  drum  is  fitted  with  ribs  inside  to  prevent  the 
powder  simply  sliding  round  in  a  cake.  The  exit  is  covered  with  wire  gauze  and 
cotton  wool  to  prevent  dust  being  drawn  into  the  condenser.  The  man-hole 
lid  tits  air-tight,  and  can  be  held  on  by  means  of  thum-screws,  but  during 
the  drying  these  screws  are  removed  so  that  the  lid  is  held  on  by  the  vacuum 
only.  If  pressure  arises  at  any  time  during  the  drying  the  lid  will  at  once 
fall  off  and  relieve  the  pressure.  The  temperature  of  the  powder  should 
never  exceed  about  50°  C.  (122°  F.).  The  powder  as  it  comes  from  the  drums 
contains  3  or  4  per  cent,  of  water  and  solvent.  The  drying  is  completed  on 
trays  in  a  drying  stove.  When  dry  it  is  sifted  so  as  to  remove  the  grains  that 
are  too  large  or  too  small  :  these  are  added  in  small  proportion  to  a  further 
charge  in  the  milling  operation.  Finally,  the  powder  is  tested  for  stability  and 
ballistics,  and  carefully  blended  with  other  batches  so  as  to  obtain  the  standard 
results.  But  before  the  final  tests  are  made  the  powder  should  be  kept  for  a 
month  or  two  in  order  that  it  may  take  up  the  normal  amount  of  moisture. 
In  ease  of  necessity  it  can  be  "  aged  "  artificially  by  exposing  it  for  a  few 
hours  to  a  hot  moist  atmosphere,  but  natural  ageing  is  more  satisfactory. 

This  scheme  of  manufacture  has  been  varied  in  many  ways.  The  incorpora- 
tion, for  instance,  can  be  performed  in  drums  with  lignum  vita?  balls.  The 
mass  can  then  be  pressed  and  broken  up  into  grains  of  the  desired  size  much 
as  is  done  with  black  powder.  Granulation  can  also  be  effected  by  sprinkling 
the  powdery  material  with  water  and  then  rotating  in  a  drum.  Various 
solvents  have  been  used  by  different  powder-makers  :  mixtures  of  ether  and 
alcohol,  acetone  and  alcohol,  and  acetone  and  ether  have  been  employed. 
Ether  is  very  volatile  and  consequently  the  losses  are  considerable. 
Ether-alcohol  only  partially  gelatinizes  the  nitro-cellulose  unless  the  degree 
of  nitration  is  low.     Benzol  is  sometimes  added  to  moderate  the  action. 

According  to  C.  E.  Munroe,1  the  following  method  is  adopted  in  America  Americai 
for  the  production  of  shot-gun  powder  with  fibres  entirely  gelatinized.  The  me 
manufacture  is  conducted  in  a  stationary  still  of  copper  about  5  feet  in  diameter 
with  conical  ends.  A  shaft  extends  downwards  through  a  stuffing  box  in  the 
top  to  a  point  near  the  bottom.  At  intervals  of  about  8  inches  horizontal 
arms  are  attached  to  this  shaft  ;  they  extend  almost  to  the  walls  on  either 
side.  Five  of  these  are  square  in  cross-section  and  about  1  inch  thick,  but 
the  sixth  bar.  which  is  the  top  one,  is  flattened  out  so  as  to  form  paddles 
which  slant  in  the  direction  of  motion  of  the  shaft  in  such  a  way  as  to  smooth 
down  the  surface  of  the  contents  of  the  still.  The  height  from  the  bottom 
to  the  toj)  stirrer  blades  is  about  6  feel  '■>  inches. 

The  orifice  at  the  bottom  of  the  still  having  first  been  closed,  the  vertical 

shaft  is  set  in  rotation  at  a  speed  sufficient  to  maintain  the  particles  of  gun- 

1  U.S.  Census  //»//..  92,   L908,  p.  84. 


326 


EXPLOSIVES 


cotton  in  mechanical  suspension  in  the  solution:  this  rotation  is  maintained 
during  the  whole  of  the  j^rocess.  Water  in  which  5  per  cent,  of  barium  nitrate 
and  2  per  cent,  of  potassium  nitrate  have  been  dissolved  is  then  pumped  into 
the  -till,  and  finely  pulped  gun-cotton  is  thrown  in  through  an  opening  in  the 
upper  part.  In  all  4.~>o  11).  of  fresh  gun-cotton  and  BOme  250  lb.  of  dust  and 
tine  grains  from  previous  granulations  are  introduced.  More  of  the  nitrate 
solution  is  pumped  in.  and  finally  the  opening  is  closed,  and  an  emulsion  is 
pumped  in  consisting  of  25  to  50  per  cent,  amyl-acetate  in  nitrate  solution. 
The  surface  of  the  liquid  should  now  be  up  to  the  top  stirrer  blades. 

The  material  now  begins  to  granulate,  and  the  progress  of  the  granulation 
is  observed  by  withdrawing  a  little  of  the  mixture  through  a  small  orifice 
near  the  bottom  of  the  still.  When  granulation  has  been  effected  throughout 
the  mass,  which  is  within  five  minutes  of  the  time  when  the  introduction  of 
the  emulsion  into  the  still  was  commenced,  steam  is  turned  into  the  jacket 
surrounding  the  lower  portion  of  the  still.  Heating  is  continued  for  five  or 
six  hours,  by  which  time  practically  all  the  amyl-acetate  has  been  distilled 
over  together  with  some  of  the  water.  This  is  condensed  and  the  amyl-acetate 
parated.  A  gate  valve  in  the  bottom  of  the  still  is  now  opened,  and  the 
mixture  of  water  and  granulated  powder  is  drawn  off  into  a  draining  tank. 
After  draining  it  is  dried,  sized,  blended  and  packed.  The  strength  and 
amount  of  the  emulsion  used  depend  upon  the  amount  and  quality  of  the 
gun-cotton  ;  the  best  proportions  are  ascertained  by  experience.  The  finished 
powder  is  coloured  to  Buit  the  taste  of  customers. 

The  older  powders,  Schultze  and  Amberite,  are  42-grain  powders,  that  is 
to  say  the  charge  required  for  an  ordinary  12-bore  cartridge  is  42  grains,  and 
this  quantity  occupies  the  same  space  in  the  cartridge  as  82  grains  of  black 
sporting  powder.  Other  42-grain  powders  are  Ruby,  Felixite.  Primrose 
Smokeless,  Cooppal  No.  1  andK.S.  Some  of  these  are  still  used  extensively, 
but  there  is  a  growing  demand  for  powders  of  which  smaller  charges  are 
required,  the  principal  advantage  of  which  is  that  they  give  a  decidedly 
lighter  recoil,  for  the  powder  products  are  ejected  from  the  muzzle  of  the  gun 
with  higher  velocity  than  the  shot.  It  is  also  claimed  that  they  are  quicker. 
Reduction  of  charge  is  effected  by  using  a  nitro-cellulose  of  higher  nitrogen 
content,  and  reducing  the  proportion  of  the  other  constituents.  These  changes 
increase  t  he  rate  of  burning,  so  in  order  to  prevent  t  he  product  ion  of  dangerous 
pressures  in  the  gun  it  is  necessary  to  gelatinize  the  nitro-cellulose  more 
completely.  A  33-grain  powder  can  be  made  in  much  the  same  manner  as  is 
described  above,  except  that  after  the  grains  have  been  formed  and  hardened 
a  portion  of  the  nitrates  is  washed  out  by  Bteeping  the  materials  in  water. 
A  well-known  33-grain  powder  of  English  manufacture  is  Smokeless  Diamond; 
Eenrite  is  another  of  this  class  :  both  these  are  in  the  form  of  black  grains. 
K.C  No.  3  is  a  iJ.'!  grain  powder  too;    it  is  coloured  \  ellou   with  amine.      Other 


FAST-BURNING  SMOKELESS   POWDERS 


327 


33-grain  powders  are   Empire,   K.S.G.,   Lightning,   Red   Star,     Stowmarket 
Smokeless,  Vicmos  and  Emerald. 

By  taking  a  further  step  in  the  same  direction  the  charge  can'Jbe  reduced  Thirty-gn 
to  as  little  as  30  grains.  The  nitro-cellulose  is  mixed  with  a  small  proportion  pow  er* 
of  "  reducers  "  and  several  times  its  weight  of  barium  and  potassium  nitrates. 
It  is  then  incorporated  in  a  Werner  and  Pfleiderer  machine  with  sufficient 
acetone  or  other  suitable  solvent  to  gelatinize  it  entirely.  The  dough  is  then 
formed  into  small  cubes  or  prisms  by  processes  similar  to  those  employed 
for  riHe  powders,  and  after  drying,  the  mineral  nitrates  are  dissolved  out  as 
completely  as  possible  with  warm  water.  Only  about  5  per  cent,  are  left  in. 
Schultze  Cube  Powder  is  an  instance  of  a  30-grain  powder  produced  by  a 
process  of  manufacture  of  this  sort. 


"^  * 

~ 

o> 

oo  m 

i. 

- 

—           M~ 

.5     N 

&  3 

£  X/l 

i- 

c 

-a 
2 
< 

o 

CO 

0  .* 

Wee 

'5 
o 
e 

a 

7.-2 

o       .S  "43 

<*             2  ~ 

Nitroglycerine    . 

37-6 

Nitro-cotton 

— 

710 

59-2 

790 

— 

521 

86-4 

940 

98-6    62-3 

Xitro-lignin 

80-1 

— 

— 

— 

621 

— 

— 

— 

—       — 

Dinitro-toluene    . 

— 

— 

15-7 

— 

— 

19-5 

— 

3-5 

—       — 

Potassium  nitrate 

— 

1-2 

1-3 

4-5 

1-8 

1-4 

— 

— 

—       — 

Barium  nitrate  . 

10-2 

18-6 

170 

7-5 

261 

22-2 

5-7 

— 

—       — 

Camphor    .... 

41 

—    1   — 

Wood -meal 

— 

1-4 

5-2 

3-8 

— 

2-7 

— 

— 

—       — 

Vaseline     .... 

7-9 

5-8 

— 

— 

4-9 

— 

2-9 

— 

—    ,   — 

Starch         .... 

— 

— 

— 

— 

3-5 

— ■ 

— 

— 

—  !  — 

Lamp-black 

— 

— 

— 

— 

— 

— 

1-3 

— 

—  I  — 

Pot.  ferricyanide 

■ — 

— 

— 

— 

— 

— 

2-4 

— 

—     — 

Calcium  carbonate 

— 

— 

0-6 

— 

— 

— 

— 

— 

—  1  — 

Ash 

— 

— 

— 

— 

0-9 

— 

0-9 

—  !  — 

Volatile  matter  . 

1-8 

2  0 

10 

11 

1-6 

1-2 

1-3 

16 

1-4      01 

Calories  per  g.    . 

742 

745 

755 

762 

786 

807 

845 

896 

L014    1286 

Permanent  gas,  c.c.  per  g. . 

763 

635 

695 

718 

576 

600 

725 

705 

669     591 

Aq.  vapour,  c.c.  per  g. 

152 

156 

131 

158 

160 

126 

14l> 

169 

206     234 

Total  vol.  gas  X.T.P. 

915 

791 

816 

876 

736 

726 

871 

874 

875     825 

Compn.  permanent   gas  p.C. 

CO,      .         .        . 

8-9 

120 

118 

11-9 

15-5 

14-8 

14-6 

190 

21-3    32-2 

CO        .... 

52-7 

50  0 

51-3 

521 

4ti  7 

49-5 

49-9 

4  .->•:? 

18-2    371 

1  II,     . 

10 

0-4      0-8 

0-5 

0-8 

0-7 

0-6 

0-8 

0-4      0-4 

H, 

27-0 

26-6    23-7 

23-9 

230 

18-8 

22-2 

21-5 

101     10  1 

X, 

10-4 

121     12-4 

lit. 

1  H> 

lli-2 

12  7 

13-4 

14  s    20-2 

Relative  temperature 

106 

12:}     I3f> 

L36 

L37 

139 

150 

urn 

161      204 

28 


EXPLOSIVES 


The  above  Table,  published  in  H><»4  byMacnab  and  Leighton,1  gives  the 
composition  of  the  principal  Bhot-gun  powders  at  that  time  in  use  in  England, 
together  with  the  amount  of  heat  generated  in  the  calorimetrie  bomb  and  the 
composition  of  tin-  products  of  explosion.  <  >f  these,  Shot-gun  Rifleite,  Sporting 
Ballistite  ami  Cannonite  were  condensed  powders.  ^^  vh<it-Lrun  Rifleite 
and  Cannonite  arc  no  longer  made. 

Sporting  ballistite  is  made  in  much  the  same  manner  as  rifle  ballistite, 

;>t   that  after  the  sheets  have  been  rolled  out.  acetone  is  added  and  the 

rolling  is  repeated,  so  that  the  finished  sheets  are  only  about  0-005  inch  thick 

and  look  like  oiled  silk.     These  are  cut  into  small  Makes.     The  normal  charge 

of  a   12-bore  cartridge  is  only  26  grains. 

In  France  the  manufacture  of  sporting  powders  forms  part  of  the  State 
monopoly  of  explosives.  The  following  Table  gives  the  composition  of  the 
powders  made  : 


Poudre 

s. 

J. 

M. 

T. 

Nitro-cotton        .... 

i;:, 

83 

71 

100 

Barium  nitrate  .... 

29 

— 

20 

— 

Potassium  nitrate 

6 

— 

5 

— 

Am.  bichromate 

U 

— 



a&ium  bichromate 

— 

:: 

— 

— 

iphor    ..... 

— 

— 

3 

— 

Rinding  material 

— 

. — 

1 

— 

Moisture     ..... 

2 

3 

— 

1-5 

1'ri'                ...       Fr. 

28 

29 

30 

32 

The  following  details  of  manufacture  are  given  in  P.etS.,  li*12.  xvi..  pp. 
99,   1"".  andVennin  et  Cheneau,  Poudres  <t  Explosifs,  pp.  434  437: 

Poudre  S.  The  nitro-cotton  consists  of  37  parts  of  CP,  and  2n  ot  I  1'. 
Tin-  materials  are  incorporated  under  light  edge  runner-,  dried  and  partly 
gelatinized  with  35  per  cent,  of  ether-alcohol.  The  dough,  which  i>  not  very 
coherent,  is  formed  into  grains  by  simply  passing  it  through  a  sieve.  The 
Lrrain>  are  dried,  sifted,  hardened  if  necessary  with  ether-aleohol  and  again 
dried  and  sifted.2 

Poudre  J.  A  mixture  of  nitro-cottons  is  used  containing  30  per  cent, 
soluble  in  ether-alcohol.  This  i-  dehydrated  with  alcohol  and  mixed  with 
tin-  bichromates  in  an  incorporator.  Then  14  per  cent,  of  ether-alcohol 
(56     B,  -p.    t.  0-760)  i-  incorporated  in.  and  the  resulting  dough  i-  pre* 


1  .1.  Soc,  Ohem.  Ind.,   1<*>4.  p.  298. 

2  For  earlier  method  set    /'.  <t  >..   1890,  voL  iii.,  p.   13. 


FAST-BURNING   SMOKELESS   POWDERS  329 

into  strips  which  are  cut  into  cubes.  These  are  then  converted  into 
grains  of  irregular  shape  in  a  granulator  consisting  of  grooved  cylinders, 
and  then  the  powder  is  drummed,  sifted  and  dried  with  cold  air.  The 
finest  siftings  are  used  for  pistols  and  practice  ammunition.  The  presence 
of  bichromates  makes  the  powder  sensitive  and  unpleasant  to  manu- 
facture. It  is  cheaper  than  Poudre  M.  The  gravimetric  density  is  0-65  to 
0-70. 

Poudre  M.  The  nitro-cotton  used  has  a  solubility  of  only  15  to  20  per 
rent.  After  drying  to  5  per  cent,  moisture  it  is  gelatinized  with  50  per  cent, 
of  ether-alcohol  of  56°  B.  This,  aided  by  the  camphor,  causes  a  superficial 
gelatinization  and  coats  the  nitrates.  The  mass  is  ground  under  edge  runners 
weighing  500  kg.  with  the  addition  of  water  and  alcohol  coloured  yellow  with 
auramine.  Then  it  is  granulated  and  drummed.  During  the  latter  process 
the  grains  are  sprayed  with  ether-alcohol  containing  1  per  cent,  of  collodion 
cotton  and  1  to  2  per  cent,  of  camphor,  which  causes  a  further  gelatinization 
of  the  surface.  The  powder  is  then  dried  and  re-drummed,  several  times 
if  necessary,  until  the  required  ballistics  are  obtained.  It  is  sifted  and  only 
the  grains  between  1-4  and  0-65  mm.  are  retained.  There  are  about  3500 
of  these  to  a  gramme.  The  gravimetric  density  is  0-465  to  0-485.  This  is 
the  most  used  of  the  French  sporting  powders. 

Poudre  T.  Gun-cotton  CPi  is  conrpletely  gelatinized  with  acetone.  2  per 
cent,  of  saltpetre  being  added.  The  dough  is  pressed  into  strips  1-5  mm. 
thick,  which  are  then  rolled  down  to  015  mm.  and  cut  into  small  squares 
of  1-5  mm.  side.  The  powder  is  then  steeped  in  water  and  dried  like  Poudre 
BF,  and  finally  drummed  with  a  little  gum  and  graphite  to  make  it  more 
progressive.  There  are  about  400  flakes  to  the  gramme,  and  the  gravimetric 
density  is  0-55  to  0-58.  This  powder  is  superior  to  the  other  French  sporting 
powders  but  more  expensive. 

The  following  are  the  normal  charges  of  a  16-bore  gun  : 

Powder  Charge 

Black       ....  4-5  grammes. 

J 2-6 

M 21 

T 1-9 

Dissatisfaction  has  been  expressed  with  regard  to  these  French  spoiling 
powders,  and  in  1908  the  .Minister  of  War  instructed  the  Committee  of  the 
service  of  "  Poudres  et  Salpetres  "  to  compare  them  with  foreign  powders. 
Comparative  experiments  were  carried  out  with  Poudre  T.  Sporting  Ballistite 
and  the  German  condensed  powder  Mullerite.  and  it  was  admitted  that  the 
results  from  the  French  powder  were  more  Irregular.  The  sales  of  Poudre  T 
amounted  to  22,358  kg.   in    L909  and  2(1.123  in   1010. 


330 


EXPLOSIVES 


German 
powders. 


American 
powders. 


Austrian. 


Requirements. 


Testing 

shot-gun 

powders. 


The  following  are  some  of  the  principal  German  shot-gun  powders 

Rottweil.     Square  flakes  with  metallic  Lustre.     <  barge   -  22   _      :u-3 

grains). 
Saxonia.     Square  flakes,  bluish  green.     Charge  l  "•    b      29-4  gi    ins 
liullerite.     Thin  square  flakes,  green.     Charge  aboul  35  grains.     Con- 
tains do  inorganic  salts. 
Walsrode.     Small    grains,    greyish-white    and    greyish-green,    mixed. 

Charge  2-27   _      35  0  grains). 
Adier-Marke.     Small  cylinders,  grey.     (  barge  2-00   _      30  9  grains 
Wolf-Marke.     Grains,  white  and  yellow,  mixed. 
Fasau (Pheasant).    Grains, greyish-yellow.    Charg    2-65 g. (40-9 grains). 
Tiger.     Grains,  blue-black.     No  lustre.     (  barge  2-73  g.  >421  grains). 
The  American  explosives  industry  is  largely  in  the  hands  of  the  E.  I.  du 
Pont  de  Nemours  Powder  Co.,  who  make  the  following: 
Condensed  powders  :    Infallible  and  Sporting  Ballistite. 
Bulk   powders:    Du   Pont   Smokeless.   E.   (".   Improved,   New   Schultze, 
Empire  and  Lesmok. 

In  Austria  there  is  a  State  monopoly  of  explosives.  Information  about 
the  sporting  powders  is  given  in  8.S.,  1909,  p.  413.  but  their  quality  has  been 
decried.1 

The  requirements  of  a  good  shot-gun  powder  are:  (a)  That  it  shall  be 
reliable  and  constant  in  its  qualities  :  this  is  as  important  as  in  the  case  of 
(.t her  gunp(»wder>.  and  somewhat  more  difficult  to  attain  :  great  care  in 
manufacture  and  thorough  blending  are  necessary.  (6)  It  should  burn  cleanly, 
leaving  little  residue  in  the  gun.  and  what  residue  there  is  should  be  alkaline 
in  reaction  and  easily  removed.  \r)  It  should  give  good  results,  even  when 
Loaded  into  cheap  cartridge  cases,  with  indifferent  wadding  and  light  shot 
charges,  {d)  It  should  be  quick  in  ignition  :  a  delay  of  a  few  thousandths 
of  a  second  in  the  time  that  elapses  between  pulling  the  trigger  and  the  shol 
Leaving  the  muzzle  makes  a  considerable  difference  in  the  accuracy  of  the 
shooting  ;  smokeless  powders  dutd  considerably  faster  than  black,  (c)  It 
should  not  be  greatly  affected  by  exposure  to  hot  or  moist  air.  </)  It  should 
occupy  aboul  the  same  space  as  the  equivalent  charge  of  black  ]  owder  :  in 
the  manufacture  of  cartridge-  the  charges  are  measured  and  not  weighed, 
and  if  the  powder  be  very  dense,  there  is  considerably  greater  danger  of  an 
extra  large  charge  being  introduced  accidentally. 

To  test  shot-gun  powders  they  are  Loaded  into  cartridges,  the  ballistics 
of  which  arc  then  measured.  The  velocity  of  the  shot  is  determined  usually 
over  a  range  of  20  yard-  from  the  muzzle  by  means  (,f  an  electric  chronograph. 
One  of  the  currents  passes  through  a  wire  before  the  muzzle  of  the  standard 
gun,  and  the  other  through  a  wire  screen  or  a  spring  contact  on  the  back 

1  8et   >.>..   L910,  p.  !  - 


FAST-BURNING   SMOKELESS   POWDERS 


331 


Rottweil 


Adler-Marke 


Saxonia 


Wolf-Marke 


Walsrode  Fasan 

Fig.  Go.     German  Smokeless  Shot-Gun  Powders  (Thorner,  S.S.,   I'.ioT.  p.    123). 


EXPLOSIVES 

..f  an  iron  target.  An  advantage  of  the  spring  contact  is  that  the  second 
current  cannot  be  interrupted  prematurely  by  one  or  two  >hot  going  ahead 
of  the  bulk  of  the  charge. 

The  press       a  are  measured  by  firing  cartridges  in  a  special  gun  of  solid 

-•  ruction.  At  1  inch  and  2 J  inches  or  «'»  inches  from  the  breach  there 
are  plug:-  passing  through  the  walls  of  the  gun  :  on  these  plugs  are  placed 
crushers  which  are  held  down  by  screws.  In  England  lead  crushers  are 
generally  used  for  testing  shot-gun  powders  instead  of  the  copper  crushers 
-  .  with  slow-burning  powders,  as  they  are  found  to  give  more  satisfactory 
results  with  the  very  variable  pressures  obtained.  The  subject  of  pressure 
measurements  will  be  dealt  with  more  fully  in  Chapter  xxix. 

The  "•pattern  "  of  the  shot  is  determined  by  firing  cartridges  from  a  gun 
of  standard  choke  at  a  whitewashed  iron  plate  generally  at  a  range  of  40 
yard-.  The  marks  of  the  shot  should  be  fairly  evenly  distributed,  and  about 
two-thirdfl  of  the  shot  should  be  within  a  circle  of  30  inches  diameter.1 

The  penetration  of  shot  can  be  measured  by  tiring  under  standard  conditions 
at  a  number  of  pieces  of  cardboard  placed  one  behind  the  other  and  counting 
the  number  of  pellets  that  penetrate  the  different  card-. 

The  recoil  of  the  standard  gun  can  also  be  measured  and  forms  a  useful 
check  on  the  other  determination-,  especially  the  velocity.     In  Fig.   66  is 
•  <h:l  proof  gun  for  taking  simultaneously  the  recoil  and  the  pressures 

at  1  inch  and  6  inches  from  the  breech.  The  velocity  and  pattern  can  also 
be  taken  at  the  >ame  time.  The  gun  weighs  50  lb.,  and  i-  -upended  5  feet 
below  its  supports  ;  it  i>  fired  by  means  of  a  pneumatic  bulb  in  order  not 
to  disturb  the  gun.  With  this  gun  numerous  investigations  have  been  carried 
out  on  behalf  of  the  Fifbl  newspaper. 

The  cartridges  for  the  12-bore  and  most  of  the  other  shot-guns  are  2\  inches 
long.  Tin-  base  and  the  powder  usually  occupy  just  1  inch,  bo  that  the  hole 
bored  to  admit  the  powder  gases  t<-  the  base  of  the  pressure  phi-  i-  hi- 
by  the  first  wad.  <  iver  the  powder  i-  placed  a  thin  card  wad.  then  a  greased 
felt  wad.  then  another  thin  card,  then  the  charge  of  Bhot,  and  finally  a  thicker 
card  wad.  The  space  above  the  -hot  wad  should  be  about  5  inch  :  this  is 
turned  over  inward-  by  means  of  a  special  machine  so  a-  to  hold  the  Bhot 
wad  in  place,  and  a  pull  of  about  50  lb.  should  be  required  to  extract  it.     The 

-     re  usually  adjusted  to  give  a  velocity  over  the  20  yards  1 
of  1050  to  1080  feet  per  second  with  a  chamber  pressure  of  :{  to  :>  :t  tons  per 
square  inch.     If  the  velocity  be  higher  than  tin-  the  Bhot  are  deformed  and 
•.•it<l  too  much,  if  lower  the  killing  power  of  the  pellets  i-  reduced;  it  i-. 
howi  tter  for  the  velocity  to  fall  below  these  limit-  than  to  rise  above 

them,  a-  Bhooting  i-  generally  at  short  ranges.     If  the  pressure  be  too  low 

1  Y  il  ajijiliai      -  •  sing  patterns  act    Vennin  et  <  ts  et 

Expbmfa,  p.   149,  ^l-'  <>.   M  -   -  .    1915,  p.   261. 


Fig.  00.     Field  Proof  Gun 

From  Arms  and  Explosives,  1911,  p.  .",  (Webley  &  Scott) 

333 


334  EXPLOSIVES 

the  patterns  are  bad.  if  too  high  the  gun  may  be  spoilt  or  even  burst.  The 
recoil  of  the  sportsman's  gun  should  be  about  16  feet  per  second,  whereas 
that  of  an  express  ririe  is  usually  about  IT  feet  per  second,  and  that  of  a  military 
rifle,  which  is  fired  much  more  rapidly.  is  ]<»  feet  per  second.1     The  French 

_        a  velocity  of  755  feet  per  second  over  a  range  of 
15  metres  [16-4  yards    in  a  16-bore  gun  with  the  standard  loading. 

The  pressure  is  increased  by  using  felt  wads  that  are  harder  or  slightly 
_•  r  in  diameter  or  by  having  a  longer  or  harder  turnover.  The  velocity 
is  also  increased  slightly  by  the  same  alterations.  The  opposite  changes,  of 
course,  produce  the  opposite  effects.  The  ballistics  are  affected  also  by  the 
strength  and  nature  of  the  cap  in  the  cartridge  case.  If  by  adjusting  these 
elements  it  is  not  possible  to  produce  the  desired  result  it  is  necessary  to 
alter  the  weight  of  powder  or  shot,  or  both. 

Powders  for  The    propellant    for    a    trench    howitzer    has    to    fulfil    much    the    same 

requirements  as  that  for  a  shot-gun  :  a  heavy  projectile  has  to  be  given 
a  comparatively  low-muzzle  velocity  and  the  gun  cannot  withstand  a  high 
—ure.  The  difficulty  is  to  obtain  constant  ballistics  with  this  low  pressure 
in  the  chamber.  It  is  overcome  by  using  powders  of  the  same  types  as  those 
for  shot-gun-. 

Blank  powder.        Blank  powders  are  used  for  firing  time  and  other  signals,  for  manoeuvres 
and  displays,  such  as    •  in  all  cases,  in  fact,  where  it  is  required 

to  make  the  noise  of  firing  without  ejecting  a  projectile.  Difficulty  is  caused 
by  the  fact  that  there  is  no  heavy  projectile  to  offer  resistance  to  the  expansion 
of  the  powder  gases  :  consequently  as  soon  as  the  envelope  containing  the 
powder  is  burst  the  pressure  falls  almost  to  nothing.  With  black  powder  this 
•  matter  very  much,  as  the  rate  of  burning  is  not  affected  to  the  same 
extent  by  the  pressure ;  gunpowder  can  be  used  indeed  for  this  purpose 
which  is  not  good  enough  for  ordinary  cartridges.  The  rate  of  burning  of 
nitro-powder,  on  the  other  hand,  is  greatly  affected  by  the  pressure  :  there 
i<  danger  therefore  if  the  envelope  offer  a  little  too  much  resistance  or  the 
primer  be  too  strong,  that  dangerous  pressures  may  be  set  up  in  the  gun  : 
and  if  the  resistance  or  the  ignition  be  too  weak  the  report  will  be  insufficiently 
loud. 

As  in  the  case  of  -h< -t -irun  powders  the  rapidity  of  burning  is  attained 
either  by  using  a  partially  gelatinized  material,  or  a  completely  gelatinized 
one  in  a  fine  state  of  division.  In  the  Briti-h  service  the  small-arm  blank 
cartridgi  a  charge  of  2"  grains  <>f  cordite  size  20  S.<        S.C.  -lands  for 

'"sliced.""  and  this  powder  is  made  by  passing  strands  of  cordite  about  0-20 
inches  in  diameter  through  a  machine,  in  which  it  is  cut  transversely  by 
rapidly  rotating  knives  into  small  discs  having  a  thickness  of  about  00055 
inch.     For  ordnance,  however,  black  powder  is  still  used  generally.    In  France 

1  Ann-"  and  Explosives,   1908,  p.   8. 


FAST-BURNING   SMOKELESS   POWDERS  335 

a  special  powder  is  manufactured  known  as  Poudre  EF,  which  is  made  of 
nitro-cotton  and  binding  material  in  much  the  same  way  as  Poudre  M.1  In 
Spain  a  nitrocellulose  flake  powder  is  used  for  small-arm  blank  ammunition.2 

In  order  to  offer  greater  resistance  to  the  powder  gases  the  cartridge  is 
often  provided  with  a  "  mock  shot  "  made  of  hollow  wood  or  other  suitable 
material  which  breaks  up  at  the  muzzle  of  the  gun.  A  disadvantage  of  these 
is  that  they  are  liable  to  lead  to  accidents,  men  being  shot  at  short  range 
(hiring  manoeuvres.  In  Germany  a  large  proportion  of  the  wounds  thus 
caused  formerly  proved  to  be  fatal  because  the  patients  developed  tetanus. 
The  source  of  this  disease  was,  however,  traced  to  the  felt  wads  used  under 
the  mock  shot.  This  danger  is  now  guarded  against  by  sterilizing  the  felt 
wads.3 

Blank  powder  for  rifles  is  called  in  Germany  "  Gewehrplatzpatronenpulver  ' 
(Gew.  PI.  P.P.),  and  that  for  machine  guns  "  Maschinengewehrplatzpatronen- 
pulver  "  (M.  Gew.  PI.  P.P.).  The  latter  is  more  violent  in  order  to  give  sufficient 
recoil  to  work  the  Maxim  gun,  and  with  the  same  object  a  piece  is  fixed 
to  the  muzzle  with  a  narrower  bore.  In  order  to  prevent  accidents  an  appliance 
is  sometimes  fixed  on  to  the  muzzle  to  break  up  the  mock  bullet  and  deflect 
it.     In  Austria  blank  cartridges  are  called  "  Exerzierpatronen." 

1  P.  ct  S.,   16,   1912,  p.   100.  2  S.S.,   1908,  p.  284. 

3  E.  Neumann,  S.S.,   1915,  p.   220. 


CHAPTER   XXIV 
SOLVENTS 

Solvents  available  :    Ether-alcohol  :    Nature  of  colloids  :    Manufacture  01  act- 
tone  :    Permanganate  test  :    Impurities  :    Acetone  from  starch  :    Acetone  from 
acetylene  :     Recovery    of    solvents  :     Acetone    recovery  :     Volatility    of    nitro- 
glycerine :    Vapour  explosions  :    Toxicity  of  vapours 

In  the  powders  first  introduced.  Schultze,  E.C..  Poudre  B.  the  solvent  used 
was  a  mixture  of  ether  and  alcohol,  which  had  been  employed  in  making 
collodion  solutions  for  many  years.  When  the  English  Government  intro- 
duced cordite  in  l*ss.  they  adopted  a  solvent,  which  had  been  but  little  used 
previously  except  in  the  laboratory,  namely,  acetone.  This  pi  asesses  the 
advantage  that  it  can  dissolve  gun-cotton  even  of  the  highest  degree  of 
nitration. 

In  the  lacquer  and  celluloid  industries  various  solvents  for  nitro-eeUulose 
are  used  in  order  to  obtain  different  specific  effects.  Amyl-acetate  especially 
i-  much  employed  in  the  preparation  of  lacquers.  Its  great  value  lies  in  the 
fact  that  it  boils  at  a  high  temperature  :  consequently  the  surface  docs  not 
become  cooled  by  rapid  evaporation,  and  so  condense  water  from  the  air. 
Moreover,  from  a  mixture  of  amyl-acetate  and  water  the  latter  evaporates 
proportionally*  much  faster  than  the  former.  Consequently  the  solution  of 
nitro-cellnlose  gradually  sets  to  a  clear  solid  film,  as  the  amyl-acetate  evapo- 
rates, whereas  if  only  very  volatile  solvents  such  as  ether  and  alcohol  are 
used.  Mater  accumulates  more  and  more,  until  it  precipitates  the  nitrocellulose 
in  an  opaque  form. 

In  the  manufacture  of  military  and  title  powders  there  are  not  many 
different  solvents  used.  If  gun-cotton  with  some  13  per  cent,  of  nitrogen 
be  the  base,  either  acetone  or  ethyl-acetate  is  used,  generally  the  former. 
If  a  "  soluble  "  nitro-cotton  be  the  base,  ether-alcohol  is  usually  employed. 
In  Poudre  B  amyl-alcohol  was  formerly  added  for  a  purpose  somewhat  sim  lar 
to  that  for  which  amyl-acetate  is  used  in  lacquers.  For  sporting  shot-gun 
powders  a  somewhat  wider  range  of  solvents  is  in  use.  and  they  are  often 
mixed  in  order  to  produce  certain  specific  effect-. 

The  subject  of  the  solubilities  of  nitro-celluloses  in  the  various  simple  and 
mixed   solvents   has  never  been   thoroughly  investigated,  although  it   is  of 

336 


SOLVENTS  337 

considerable  practical  and  theoretical  importance.  De  Mosenthal  gave  a 
long  list  of  solvents  that  have  been  mentioned  in  patent  specifications,1  but 
in  the  absence  of  information  as  to  the  sort  of  nitro-cotton  or  the  conditions 
under  which  it  is  dissolved,  the  list  is  not  of  great  value. 

Gun-cotton  containing  about  13  per  cent,  nitrogen  only  dissolves  to  a 
small  extent  in  ether-alcohol,  but  is  totally  dissolved  or  gelatinized  by  acetone 
and  other  ketones,  by  aldehydes  such  as  benzaldehyde  and  furfural,  by  esters 
such  as  ethyl-acetate  (acetic  ether),  by  acid  anhydrides  such  as  acetic  anhy- 
dride, and  by  some  nitro-compounds  such  as  nitro-toluene.  On  the  other 
hand,  it  is  not  dissolved  by  nitro-benzene,  nitro-phenol,  or  organic  acids 
such  as  acetic  or  formic.  Excepting  nitro-toluene  all  the  above  solvents 
for  gun-cotton  contain  the  group  :CO  connected  with  two  other  radicles  other 
than  hydroxyl,  — OH. 

"  Soluble  "  nitro-ceHuloses  are  distinguished  from  gun-cotton  by  the  fact  Etheral-cohol 
that  they  are  soluble  in  a  mixture  of  ether  and  alcohol  :  of  any  ether  and 
any  alcohol ;  whereas  they  are  practically  insoluble  in  the  ether  alone  and 
only  dissolve  with  difficulty  in  absolute  alcohol.  From  determinations  of 
the  viscosity  of  mixtures  of  various  alcohols  and  ethers  F.  Baker  2  finds 
evidence  of  the  formation  of  compound  molecules  such  as  C2H60,  C4H10O, 
and  it  is  these  apparently  which  have  the  property  of  dissolving  the  nitro- 
cellulose ;  but  Bingham  has  pointed  out  that  the  evidence  is  not  conclusive.3 
An  alternative  theory  is  that  the  ether  only  plays  a  passive  part  in  causing 
the  associated  molecules  of  alcohol  (R.OH)n  to  split  up  into  simple  molecules 
R.OH,  which  latter  dissolve  the  substance.  But  this  theory  is  inconsistent 
with  some  of  the  facts  :  other  liquids  which  are  known  not  to  combine  with 
the  alcohol,  such  as  benzene,  cannot  be  substituted  for  ether  ;  then  again 
the  most  associated  alcohols,  methyl-  and  ethyl-alcohols,  have  the  greatest 
solvent  powers  when  mixed  with  ether  ;  also  the  solvent  power  of  a  mixture 
of  ether  and  alcohol  is  increased  by  reduction  of  temperature.4  All  these 
facts  are  consistent  with  the  theory  that  it  is  the  compound  molecules  of  ether- 
alcohol  that  have  the  solvent  power,  but  not  that  this  property  resides  in 
the  unassociated  molecules  of  alcohol.  The  solubility  in  various  mixtures 
has  been  investigated  by  Stepanow,5  who  found  that  the  maximum  solubility 
is  obtained  when  the  proportion  of  ether  to  alcohol  is  3  :  2,  i.e.  when  the  two 
liquids  are  mixed  in  about  equi-molecular  proportions.  The  addition  of 
solvents  such  as  acetone  or  ethyl-acetate,  increases  the  solubility  in  ether- 
alcohol,  but  indifferent  substances  such  as  benzene,  toluene,  pyridine,  phenol, 

1  J.  Soc.   Chem.  Ind.,   1904,  p.  295.  2  J.   Chem.  Soc,   101,   1912,  p.   1409. 

3  J.  Chem.  Soc,   103,   1913,  964. 

4  W.  Macnab  succeeded  in  dissolving  highly  nitrated  "  insoluble  "  gun-cotton  in 
ether-alcohol  by  reducing  the  temperature  to  that  of  solid  carbon  dioxide. 

5  S.S.,   1907,  p.  43. 

VOL.   I.  22 


338  EXPLOSIVES 

chloroform  diminish  the  solubility,  the  diminution  being  proportional  to  the 
quantity  added.  Other  substances,  such  as  water  and  acids,  also  affect  the 
solubility,  l>ut  not  proportionally. 

Soluble  nitro-cellulose  or  collodion  cotton  is  also  dissolved  by  nitro-glycerine, 
acetic  arid.  etc.  In  the  celluloid  industry  use  is  made  of  the  solvent  power 
of  camphor,  and  there  are  a  number  of  other  substances,  solid  at  the  ordinary 
temperature,  which  have  the  same  property  :  the  dissolution  is  greatly  pro- 
moted by  the  addition  of  alcohol.  It  has  been  stated  by  Bernadou  that  at 
a  low  temperature  nitro-cellulose  is  dissolved  by  ether  alone. 

Lunge  and  Bebie  1  found  that  a  nitro-cotton  containing  about  11  per  cent. 
N  \\as  soluble  in  absolute  alcohol,  but  insoluble  in  95  per  cent,  alcohol.  Ennea- 
nitro-cellulose  (12  per  cent.  N)  only  dissolved  to  the  extent  of  70  per  cent. 
in  absolute  alcohol,  whilst  a  deka-nitro-cellulose  (12-75  per  cent.  X).  although 
completely  soluble  in  ether-alcohol,  only  dissolved  in  absolute  alcohol  to  the 
extent  of  1-3  per  cent.  With  a  nitro-cotton  containing  11-5  per  cent.  N 
the  following  results  were  obtained  with  the  ether  and  alcohol  in  varying 
proportion^  : 

Ether  :  Alcohol  Kther  :  Alcohol 

1  :  3     Dissolve  readily  — 

1    :   ti     Lees  readily,   '•':>  pet  tout,  after  6   :    1      Dissolves  readily. 

treating  twice. 

Less  readily,  95  per  cent. 
92  1   per  cent,  dissolved. 


9   : 

1 

!_'  More  readily,  !">  per  cent. 

after 

12 

:    1 

treating  once. 

i' 1   95*6  per  rent. 

27   : 

1 

Similar  experiments  have  been  carried  out  by  A.  Matteoschat  with  a 
nitro-cellulose  <>f  medium  solubility  containing  12-95  per  cent,  nitrogen.2 
Th.-  solvents  used  consisted  of  pure  ether  and  pure  alcohol  containing  varying 
percentages  of  water  mixed  in  different  proportions.  To  prevent  surface 
gelatinizatiorj  of  the  nitro-cellulose  the  alcohol  was  added  first  and  then  the 
ether.     The  following  were  the  solubilities  found: 

Strength  of  Alcohol  by  Volume 
Ether  :  Alcohol    . 
1:2. 
1:1. 

2:1. 
3:1. 

It   will  be  seen  that  in  mixtures  rich  in  ether  the  solubility  is  increased 

by  the  addition  of  a  moderate  proportion  of  water.  T.Chandelon  has  found 
that  the  addition  of  water  also  diminishes  the  viscosity  of  the  solution  of 
nitro-cellulose  in  ether-alcohol,  and  that  it  makes  no  difference  whether  wet 

1  Aug.,   1901,  p.   637.  2  S.S.,   1914,  p.   105, 


90% 

80?c 

32-4 

— 

— 

— 

52-3 

42  :; 

2s  7 

14-2 

40*5 

52  4 

53*0 

4.VO 

250 

42-4 

.->:{-<  i 

.",  7  5 

SOLVENTS  339 

nitro-cellulose  be  dissolved  in  water-free  solvent,  or  dry  nitro-cellulose  in 
ether-alcohol  containing  water,  provided  that  the  final  composition  of  the 
solution  be  the  same.1 

The  dissolution  of  a  colloidal  substance,  such  as  nitro-cellulose,  differs  Nature  ol 
fundamentally  from  that  of  crystalline  substances,  such  as  sugars  or  the  collolds• 
ordinary  mineral  salts.  Strictly  speaking  colloids  do  not  form  solutions, 
but  with  suitable  liquids  they  form  what  are  termed  "  sols,"  which  are  inter- 
mediate between  solutions  on  the  one  hand  and  suspensions  and  emulsions 
on  the  other.  The  latter  consist  of  small  particles  of  solid  or  liquid  respect- 
ively suspended  in  a  liquid  medium,  the  particles  being  of  such  size  that  they 
can  be  seen  under  moderate  magnification.  In  a  true  solution  the  dissolved 
substance  consists  of  individual  molecules  floating  about  in  the  solvent. 
No  sharp  line  of  distinction  can  be  drawn  between  sols  and  solutions  on  the 
one  hand  and  emulsions  and  suspensions  on  the  other.  A  molecule  has  a 
diameter  of  about  a  ten  millionth  of  a  millimetre  in  the  case  of  the  simplest 
conrpounds  up  to  rather  more  than  a  millionth  in  the  case  of  very  complex 
substances.  The  extreme  limit  of  visibility  through  a  microscope  is  about 
a  ten-thousandth  of  a  millimetre.  The  size  of  the  disperse  particles  in  a 
sol  may  be  considered  to  be  comprised  between  the  limits  of  a  thousandth 
to  a  millionth  of  a  millimetre.  If  not  smaller  than  about  5  millionths  they 
can  be  detected  as  bright  spots  when  illuminated  by  a  powerful  beam  of  light 
against  a  dark  ground  in  the  ultra-microscope.  One  of  the  properties  of 
particles  of  this  size  is  that  they  show  a  continuous  oscillating  movement, 
known  as  the  Brownian  movement,  when  observed  under  the  microscope  or 
ultra-microscope.  Colloid  substances  are  divided  into  two  classes,  suspens- 
oids  and  emulsoids,  according  as  their  sols  resemble  suspensions  and  emulsions 
respectively.  Colloidal  metal  sols  belong  to  the  former  class  ;  silicic  acid, 
gelatine  and  other  organic  colloids,  including  nitro-cellulose,  belong  to  the 
emulsoid  class.  When  a  colloid  of  the  latter  class  is  immersed  in  a  suitable 
liquid  it  swells  up.  Thus  hide  substance  when  soaked  in  water  swells  up 
without  passing  into  the  liquid  phase,  and  india-rubber  behaves  similarly 
in  ether.  Gelatine  swells  up  in  water  in  a  similar  manner,  but  if  the  mixture 
be  heated  a  sol  is  obtained  which  on  cooling  sets  again  to  a  "  gel."  Unvul- 
canized  rubber  in  chloroform  or  benzene  swells  up  and  at  the  same  time  forms 
a  sol,  and  nitro-celluloses  behave  similarly  with  solvents.  When  a  colloid 
swells  there  is  always  evolution  of  heat  and  the  volume  is  always  smaller 
than  the  combined  volume  of  the  colloid  and  the  liquid  before  the  swelling 
took  place.  From  this  it  may  be  deduced  according  to  le  Chatelier's  theorem, 
that  heat  must  hinder  swelling  whilst  cold  and  pressure  favour  it.  There  is 
a  considerable  rise  of  temperature  when  acetone  or  ether-alcohol  is  added  to 
gun-cotton,  but  only  a  slight  rise  with  alcohol  alone  and  nunc  with  ether.  It 
J  Bui/.  Soc.  ofwm.  Bclg.,   1912,  no.   11,  S.S.,  1914,  p.   194. 


340  EXPLOSIVES 

Lb  supposed  that  the  ><>1  <>f  an  emulsoid  consists  of  two  liquid  phases  differing 
from  one  another  considerably  in  composition,  but  a>  the  temperature  i-  i     - 
the  compositions  "f  the  two  phases  approach  one  another,  as  Lb  the  case  with 
partially  miscibJe  liquids.     Many  gels  when  examined  under  the  micros 
show  a  cellular  <>r  webbed  structure,  whence  it  i-  concluded  that  they  also 
consist  of  two  phases,  hut  this  structure  has  only  been  observed  in  Lrel-  obtained 
l>y  coagulating  sols  by  heat  or  the  addition  of  some  other  substance.    When 
the  gels  arc  prepared  by  cooling  the  gel  or  evaporating  off  the  solvent  this 
structure  is  not  observed,  and  it  is  with  such  gels  as  these  that  we  are  con- 
cerned in  the  case  of  smokeless  powders  and  blasting  gelatine.     When  a  gel 
is  subjected  to  pressure  under  such  conditions  that  the  solvent  alone  can  escape, 
some  of  the  solvent  escapes,  the  amount  depending  upon  the  pressure  applied 
and  the  composition  of  the  gel :  the  larger  the  quantity  of  solvent  present  the 
more  easy  it  is  to  express  part  of  it.     The  last  portion  of  solvent   is  hov 
very  difficult  to  remove  by  pressure  or  even  by  heat,  and  this  difficulty  is 
increased  by  the  fact  that  diffusion  is  very  slow  in  a  stiff  and  concentrated 
gel,  although  in  a  sol  containing  much  solvent  it  is  almost  as  rapid  a-  in  the 
pure  liquid. 
Manufacture  Acetone  i-  made  by  the  dry  distillation  of  acetate  of  lime,  which  in  turn 

of  scptonp  *  * 

i-  a  product  of  the  dry  distillation  of  wood.  Beech,  birch  and  the  American 
maple  are  the  tree-  most  concerned,  as  they  yield  comparatively  large  quan- 
tities of  acetic  acid  on  distillation.  Coniferous  trees,  the  fir  and  pine,  on  the 
other  hand  yield  little  acetic  acid  :  the  most  valuable  product  from  their 
distillation  i>  turpentine.  Even  from  the  most  suitable  woods  the  yield  of 
acetone  i-  small  :  only  B  to  10-5  parts  of  acetate  of  lime  of  so  per  cent,  strength 
are  obtained  from  100  of  dry  wood,  and  this  in  turn  only  yields  about  20 
per  cent,  of  acetone.  Moreover,  fresh  felled  beech  or  maple  contains  about 
40  per  cent,  of  moisture.  Consequently  it  requires  from  B0  to  100 
wood  to  produce  1  ton  of  acetone,  and  the  manufacture  is  dependent  on  the 
Bupply  of  very  large  quantities  of  wood.  Attempts  have  been  made  to  manu- 
facture acetate  of  lime  and  other  products  by  the  distillation  of  sawdust, 
waste  wood  and  other  woody  materials,  but  most  of  these  undertakings  have 
hitherto  proved  imremunerative.     The  charcoal  obtained  from  these  waste 

materials  is  generally    of   little  value,  and  the    yield  of  acetate    and  w 1 

spirit   is  considerably  less  than  from  good  new  wood. 

"  Grignon,"  the  residuum  left  after  pressing  the  oil  from  olives.  i>  now 
distilled  on  a  large  scale  in  Spain,  It  yields  about  4  per  cent,  of  acetate  of 
lime  and  1-2  per  cent  of  crude  wood  spirit.  Other  waste  produ<  be  risting 
principally  of  cellulose  and  lignin  might  be  utilized  similarly  :  coffee  husk-. 
for  instance,  and  the  wood  from  which  tannin  and  dye  extract-  have  been 
made  Buch  a-  quebracho  chips.  In  course  of  time  these  material-  will  no 
doubt  be  utilized,  but  only  where  very  large  supplies  of  them  are  available. 


SOLVENTS  341 

The  first  necessity  of  a  wood  distillation  plant  is  a  plentiful  supply  of  wood, 

the  second  is  a  ready  market  tor  the  charcoal.  As  a  rule  a  plant  will  not  be 
remunerative,  unless  the  selling  price  of  the  charcoal  covers  the  cost  of  the 
wood  used.1  The  value  of  the  by-products,  acetate,  wood  spirit  and  tar, 
then  only  has  to  provide  the  cost  of  working,  interest   and  profit. 

Charcoal,  although  it  weighs  only  about  one-third  as  much  as  fche  original 
wood,  occupies  nearly  as  much  space.  Moreover,  it  is  decidedly  brittle,  and 
if  it  has  to  be  transported  very  far  by  road  or  rail,  a  large  proportion  of  it  is 
converted  into  powder,  which  has  a  comparatively  small  value.  Therefore 
a  wood  distillation  plant  should  be  situated  where  there  is  a  plentiful  supply 
of  suitable  wood,  a  ready  market  for  the  charcoal,  and  good  means  of  com- 
munication. The  by-products,  acetate,  crude  wood  spirit  and  tar,  are  corn- 
pa  latively  light  and  can  be  transported  over  considerable  distances  to  a  cent  pal 
chemical  factory  to  be  worked  up. 

These  conditions  are  present  in  many  parts  of  India.  Nevertheless  char- 
coal is  still  produced  there  in  small  kilns  and  the  valuable  by-products  are 
allowed  to  escape.  The  reason  is  that  technical  knowledge  is  deficient,  and 
capital  is  not  available  through  want  of  enterprise.  Most  of  the  acetate  of 
lime  and  acetone  are  manufactured  in  the  United  States,2  but  there  are  also 
large  plants  for  their  production  in  Hungary,  Sweden,  Russia,  and  Canada. 

By  the  destructive  distillation  of  wood  three  different  classes  of  products 
are  obtained  :  solid,  liquid  and  gaseous.  The  solid,  charcoal,  remains  in 
the  kiln  or  oven  ;  the  liquid,  crude  pyroligneous  acid,  is  recovered  from  the 
mixture  of  gas  and  vapour  by  means  of  a  suitable  condenser  ;  and  the  gases 
pass  on  and  may  be  used  either  for  heating,  or  to  drive  a  gas-engine,  but  a 
further  quantity  of  methyl-alcohol  and  acetic  acid  can  first  be  recovered  from 
them  by  scrubbing  with  water  in  a  tower.  By  distillation  and  treatment 
with  milk  of  lime  the  crude  pyroligneous  acid  is  further  separated  into  tar, 
acetate  of  lime  and  commercial  wood  spirit. 

The  acetate  of  lime  is  not  as  a  rule  worked  up  further  at  the  carbonization 
works,  but  is  sent  to  a  chemical  factory  where  large  quantities  are  collected 
and  worked  up  into  acetone,  acetic  acid,  and  various  acetates  and  derivatives 
of  acetic  acid.  There  are  two  varieties  of  commercial  acetate  of  lime,  brown 
and  grey,  which  differ  from  one  another  in  that  grey  acetate  has  had  the 
tar  removed  as  far  as  practicable,  and  the  brown  has  not.  Brown  acetate 
is  not  made  now  on  a  very  large  scale,  as  it  gives  very  bad  yield-  of  acetone 
and  acetic  acid.  Grey  acetate  generally  contains  so  to  82  percent,  of  calcium 
acetate  as  determined  by  analysis,  and  -4  to  7  per  cent,  of  water,  the  remainder 
being    made   up   of  various  impurities.      Of  the   SO   to   82   per  cent.,   however. 

several  per  cent,  consist  of  formate,  propionate  and  salts  of  other  organic  acids. 

1  Klar,  Holzverkohlung,  second  ed.,  p.  62. 
-  For  statistics  set    J .  Soc.  CJiem.   I  ml..   L914,  p.  345. 


342 


EXPLOSIVES 


The  conversion  into  acetone  is  effected  by  -imply  heating  the  acetate  at 

a  temperature  of  about  30<»    I '..  when  the  following  reactioo  takes  place: 

o  .(  II  <  ;ii  o        i  II  (  <>.<  II  .   hut   the    other  organic  calcium   salts 

react  in  a  -imilar  manner:  formic  acid  yields  aldehydes,  propionic  acid  yi  Ids 

methyl-ethyl-ketone   and   diethyl-ketone,    and   the    higher   homologues    the 

corresponding  higher  ketones. 

The  distillation  of  the  acetate 
of  lime  is  usually  carried  out  in 
a  shallow  circular  retort  heated 
by  direct   lire.      Pig.  « *> T  i-  a  view 

of  a  retort  at  the  Royal  Gun- 
powder Factory.  W  a  1 1  h  a  m 
Abbey  ;  it  is  provided  with  a 
stirring  arrangement,  H.  and 
man-holes  .4  and  ('.  for  filling 
and  emptying.  The  tubes  for 
the  gases  and  vapours  have  rods, 
A",  to  remove  any  obstruction  of 
tar.  coke  or  dust.  The  charge 
of  Mich  a  retort  is  from  300  to 
Ton  11).  After  fastening  down 
the  man-hole  the  stirring 
mechanism  is  started  and  the 
retort  is  gradually  heated  up. 
care  Ixiiiir  taken  to  avoid  over- 
heating as  far  as  possible,  as  it 
causes  the  formation  of  tar  and 
coke,  and  a  corresponding  di- 
minution of  the  yield  of  acetone. 
It  i>  not  practicable  to  dry  the 
whole  of  the  moisture  out  of  the 
acetate  before  charging  it  into 
the  retort,  as  acetone  begins  to 
be  given  off  even  at  a  moderate  temperature.  Consequently  the  first  run- 
nings of  the  retort  consist  of  water  with  only  a  little  acetone.  The  decom- 
position  of  the  acetate  doe-  not  become  active  until  the  temperature 
reaches  about  380c  c.  ;  the  bulk  of  the  distillate  come-  over  between  380 
and  400    C.     At  the  end  of  the  distillation  steam  ia  blown  through  to  remove 

the  last   portion  of  the  distillate,  and  to  render  the  residue  in   the   retort  non- 
inflammable. 

Attempts  have  been   made  to  heat    the  retort-  in  a   bath  of  lead   in  order 

to  make  the  heating  more  uniform  and  so  improve  the  yield,  but  trouble  was 


Fig.  67.     Acetate  of  Lime  Still, 


SOLVENTS 


343 


caused  by  the  oxidation  of  the  lead,  with  the  consequence  that  heat  was  lost, 
and  the  special  object  of  the  bath  was  not  attained.  Heating  in  a  stream 
of  superheated  steam  has  also  been  tried  :  a  better  yield  is  thus  obtained, 
but  the  consumption  of  fuel  by  this  process  is  considerably  greater  ;  more- 
over, it  is  only  possible  to  work  sifted,  dust-free  acetate,  which  makes  it 
very  expensive.  Another 
process,  that  has  been 
tried  and  abandoned,  was 
the  conversion  of  the 
acetic  acid  of  the  crude 
pyroligneous  acid  directly 
into  acetone  without  the 
preliminary  formation  of 
acetate.  This  was  done 
by  passing  the  acid  over 
heated  baryta  or  lime. 
A  plant  was  erected  on 
this  principle  in  Woolwich 
Arsenal,  but  it  did  not 
prove  successful,  and  was 
soon  abandoned.  The 
yields  by  this  process  were 
very  poor  ;  the  crude 
acetone   was  mixed   with 

much  unchanged   acetic   acid,  which  had  to  be   recovered  and  worked  over 
again. 

Recently  an  improvement  has  been  effected  by  heating  the  acetate  in  thin 
layers,  that  are  not  in  direct  contact  with  the  hot  walls  of  the  retort.  Fig.  68 
shows  a  retort  on  this  principle  made  by  F.  H.  Meyer,  of  Hanover.  The  trays 
of  acetate  are  placed  on  trolleys,  two  of  which  are  wheeled  bodily  into  the 
retort.  The  latter  is  heated  as  uniformly  as  possible  by  means  of  a  Dumber 
of  fires.  When  the  charge  is  finished,  the  trolleys  are  wheeled  out  and  two 
fresh  ones  are  run  in  at  otice.  Thus  loss  of  heat  is  avoided,  and  the  disagree- 
able operation  of  drawing  the  very  dusty  spent  lime  from  the  retort  is  much 
improved. 

From  the  retort  the  vapours  are  led  to  a  condenser,  which  musl  be  bo 
constructed  that  the  tubes  can  easily  be  cleaned,  as  they  are  liable  to  Ik  come 
choked  with  tar  and  dust.  The  crude  distillate  separates  into  two  layers, 
the  heavier  of  which  consists  mostly  of  water  and  acetone  with  some  methyl- 
ethyl-ketone  and  other  impurities,  the  lighter  one  of  methyl-ethyl-ketone 
and  tarry  matter  with  impurities  such  as  dumasin.  and  there  is  some  water 
and  acetone  dissolved  in  it.     The  mixture  is  pumped  into  a  tank  rendered 


Fig.  68. 


H.   Meyer's  Plant   for  the  Dry   Distillation  of 
Acetate  of  Lime. 


EXPLOSIVES 


- 


• 


alkaline  with  caustic  soda  and  allowed  to  settle.     The  heavier  lave: 
run  off.  and  the  lighter  U  vera!  times  with  water.     These  calk 

liquors  are  then  pumped  into  a  -till,  such  as  that  -  iiagranimatically 

in  Fig.  69.     The  essential  feature  of  this  is  that  part  of  the  va  <  on- 

densed  in  the  tubular  condeiw-r.  D.  and  returned  to  the  column.  C.  where  it 
flows  over  a  number  of  perforated  plates      The 

_  of  the  vapour  through  each  of  th- 
plates  is  equivalent  to  a  fresh  fractionation. 
The  remainder  of  the  vapour  -  lown  the 
tube.  F.  to  the  condenser.  D.  From  th 
liquid  flows  through  the  still- watcher.  H.  to  a 
drum  or  other  receiver.  Continuous  working 
stills  are  made  on  the  same  principle. 

With  such  a  distilling  plant  there  is  no 
difficulty  in  getting  the  acetone  free  from 
water,  but  the  removal  of  the  other  impurities 
causes  considerable  trouble.  As  the  distillate 
runs  through  the  still-watcher,  continuous 
servations  of  the  specific  gravity  are  taken 
by  means  of  a  hydrometer  floating  in  the 
liquid  :  all  that  shows  a  higher  gravity  than 
-800  is  run  into  a  separate  receptacle  for  impure 
acetone,  but  it  is  afterwards  redistilled  to  re- 
cover the  good  acetone. 

One  of  the  prineipa  L  teste  |  -plied  to  acetone 
is  the  "  permanganaT'  test  according  to  the 
specification  of  the  English  Government  1  c.c. 
of  a  0-1  per  cent,  solution  of  potassium  per- 
manganate is  added  to  100  c.c.  of  acetone,  and  the  characteristic  colour 
of  the   permanganate   must    persist    for   at  lea>t    half  an   1  «  »ulv  the 

middle  portion  of  the  distillate  will  stand  this  test  la  add* 

crude  acetone  combines  with  all  free  acid.  so   that  the  distilled 
tains  no  acid  except  a  little  carbon  dioxide.  .      iter  part  of  the  aldehyde 

is  also  removed  by  the  soda,  as  it  converts  it  into  rei  hieh  are 

not  volatile,  and  consequently  remain  in  the  still  :   the  distillate  only 
tains  traces  of  aldehyde. 

There  are  other  impurities,  however,  which  r  and  greatly  affect 

the  permanganate  te-:.     Moreover,  it  is  found  that  acetones,  which  pa--  the 
with  ease  when  quite  fresh,  fail  after  ha       g  The 

fall  of  the  t-  -n  very  rapid  at  first,  but  becoi  er  after  a  time. 

but  even  after  years  the  fall  may  still  continue.     The  fall  of  the  permang 
ate  •  _   rierally  accompanied  by  an  alteration  in  the  colour  of  the 


\L 


Still  -.fying 

Ac-  ■ 


SOl.YKXTS  :U5 

which  assumes  a  brown  colour  instead  of  remaining  colourless.  Such  deter- 
iorated acetone  is  considered  unfit  for  the  manufacture  of  cordite  and  similar 
explosives,  and  has  to  be  redistilled  before  use.  As  the  English  Governmenl 
maintains  a  Large  reserve  of  acetone,  amounting  to  several  years'  consumption, 

this  redistillation  became  a  serious  matter  not  only  on  account  of  the  actual 
cost  of  redistillation,  hut  also  because  there  was  a  considerable  loss  of  acetone 
during  distillation,  and  in  the  first  and  last  runnings.  The  cause  of  the 
deterioration  was  therefore  investigated  and  was  found  to  he  intimately 
associated  with  the  presence  of  hasie  substances  such  as  methylamine  in  the 
acetone.  If  after  the  first  distillation  in  the  presence  of  soda  the  acetone  is 
distilled  again,  hut  this  time  with  the  addition  of  a  small  excess  of  sulphuric 
acid  to  the  liquid  in  the  still,  all  basic  substances  are  entirely  removed  ;  the 
redistilled  acetone  gives  a  much  better  permanganate  test,  which,  moreover, 
falls  off  little  or  not  at  all  even  after  storage  for  several  years.1 

Of  the  various  amines  that  may  be  present  in  acetone,  the  primary  and  Amines, 
secondary  amines  are  those  that  have  the  most  deleterious  effect  on  the  keep- 
ing powers  of  acetone,  e.g.  methyl-amine,  ethyl-amine,  butyl-amine,  amyl- 
amine  ;  dimethyl-amine,  diethyl-amine.  On  the  other  hand,  ammonia  and 
tertiary  amines  such  as  trimethyl-amine  have  little  or  no  effect  upon  it.  The 
principal  amine  present  in  acetone  that  has  not  been  distilled  over  acid,  is 
mono-met hyl-amine  together  with  some  ammonia,  and  the  amount  is  usually 
between  00005  and  0-005  per  cent.  Although  these  quantities  are  small, 
they  are  sufficient  in  the  presence  of  quantities  of  aldehyde  of  the  same  order 
to  cause  a  decided  deterioration  of  the  acetone.  Ammonia  and  the  primary 
amines  form  more  or  less  stable  compounds  with  acetone,  which  are  only 
gradually  decomposed  again  during  distillation,  with  the  result  that  the  amine 
comes  over  in  varying  quantities  in  all  parts  of  the  distillate  instead  of  only 
in  the  first  runnings.  It  is  not  the  formation  of  these  compounds,  however, 
that  causes  the  deterioration  of  the  acetone,  but  the  action  of  the  amines 
on  the  traces  of  aldehyde  and  other  impurities,  or  perhaps  .simultaneous  action 
on  these  substances  and  acetone. 

The  acetate  of  lime  contains  a  considerable  proportion  of  calcium  formate,  Aldehydes 
and  this  in  the  dry  distillation  gives  rise  to  aldehydes.  Acet aldehyde  is 
probably  the  principal  one.  but  there  are  also  formaldehyde,  propionic  alde- 
hyde, and  other  higher  members  of  the  series.  Formaldehyde  readily  changes 
into  a  mixture  of  methyl-alcohol  and  formic  acid  dining  the  dry  distillation, 
and  also  during  the  distillation  with  soda.  The  formic  acid,  of  course,  remains 
in  the  still  as  sodium  formate,  hut  the  methyl-alcohol  passes  over  into  the 
distillate,  and  is  found  (specially  in  the  first  runnings.  Acetaldchyde.  when 
acted  upon  by  the  alkali,  is  largely  converted  into  aldol  and  other  high- boiling 
condensation  products  and  into  resinous  bodies,  which  remain  in  the  still. 
1  s,,    Marshall,  ./.  Soc.  Chem.   //«/..   1904,  p.  645. 


EXPLOSIVES 


Propionic  and  other  aldehydes  behave  very  much  in  the  same  way  as  acetalde- 
hvde.  The  destruction  of  the  aldehydes  is  not  complete,  however,  and  con- 
sequent^ small  traces  are  to  be  found  in  the  acetone  even  after  several 
distiUati 

The  presence  of  small  traces  of  aldehyde  can  be  detected  in  acetone  by 
the  application  of  SchifFa  reagent.  Acetone  itself  gives  a  purple  coloration, 
but  if  there  be  0005  per  cent,  of  aldehyde  or  methylal  in  it,  the  colour  is 
distinctly  stronger. 

Methyl-alcohol,  as  has  already  been  pointed  out.  is  produced  from  the 
formaldelvde.  There  are  many  other  reactions  by  which  it  can  be  formed 
from  the  constituents  of  crude  pyroligneous  acid.  As  methyl-alcohol  has  a 
boiling-point  aderabry  higher  than  that  of  acetone.  56-1°,  and  has 

practically  the  same  specific  gravity.  0-796,  it  might  be  thought  that  the 
alcohol  would  pass  over  in  the  last  runnings  of  the  distillation,  and  that  its 

nee  would  not  affect  the  specific  gravity  oi  the  acetone.  The  rev< 
is.  however,  the  case.  When  the  two  liquids  are  mixed  together,  there  is 
a  contraction,  and  consequently  the  mixture  is  more  dense  than  the  con- 
stituents. Moreover,  mixtures  containing  much  acetone  boil  at  a  lower  tem- 
perature than  acetone  itself  :  the  mixture  of  minimum  boiling-point  contains 
H  '  per  cent,  of  acetone,  and  13  5  per  cent,  of  methyl-alcohol,  and  boils 
at  55-90.1  This  mixture  has  a  specific  gravity  of  0-7997  :  it  cannot  be  separ- 
ated into  its  constituents  by  fractional  distillation  :  on  the  contrary  it  behaves 
much  as  a  simple  liquid.  Moreover,  as  its  boiling-point  is  so  near  to  that 
of  acetone  the  constant  boiling  mixture  cannot  be  entirely  separated  from 
the  acetone.  Consequently  methyl-alcohol  occurs  mostly  in  the  first  runnings, 
but  is  also  present  throughout  the  distillation.  It  is  possible  that  methyl- 
alcohol  may  have  a  deleterious  effect  upon  the  stability  of  explosives  with 
which  it  is  mixed,  through  its  liability  to  become  oxidized  to  formaldehyde, 
but  as  there  is  no  method  known  lor  the  ready  determination  of  the  amount 
of  it  in  acetone,  nor  any  process  for  separating  it  on  a  manufacturing  scale 
without  greatly  increasing  the  cost  of  the  solvent,  no  particular  attention  has 
hitherto  been  paid  to  the  matter. 

Besides  these  impurities  the  first  runnings  also  contain  some  substances 
that  are  insoluble  in  water:  if  this  acetone  be  mixed  with  twice  its  bulk  of 
water  f  irate  out   partly.     The  liquid  thus  obtained   is  a   complex 

mixture  with  a  specific  gravity  of  about  0-78  and  boiling  over  a  range  oi 
to  110°,  it  apparently  contains  various  hydro-carbons  saturated  and  unsatur- 
ated, and  also  substances  such  as  furan  <  ,H  ,0  and  sylvan  I    !!.<».      Furan 
would  be  formed  by  the  dry  distillation  of  the  calcium  salt  of  pyromucie  acid, 
one  of  the  constituents  of  the  crude  pyroligneous  acid. 

The  effect  of  these  substances  upon  the  permanganate  test  is  very  similar 
1  Jvttit,  Jour,  P  ,  1899,  3,  349. 


SOLVENTS  347 

to  that  of  aldehyde,  but  not  nearly  so  great.  The  addition  of  0-2  per  cent, 
reduces  the  permanganate  test  of  pure  acetone  from  many  hours  to  about 
100  minutes,  and  in  the  presence  of  basic  substances  there  is  a  further  slow 
fall,  which,  however,  is  not  nearly  so  rapid  as  in  the  case  of  aldehydes.  If 
0-2  per  cent,  be  present  the  acetone  becomes  cloudy  on  the  addition  of  two 
volumes  of  water.  Those  impurities  can  be  separated  by  a  special  process  of 
distillation,  for  which  see  Part  XII.  There  are  also  chemical  reactions  by 
which  these  substances  can  be  detected  and  estimated  :  such  as  the  iodine 
test  given  in  Part  XII  which  enables  one  to  estimate  the  amount  of  the 
substances  to  within  0002  per  cent.  Commercial  acetones  usually  contain 
from  002  per  cent,  to  010  per  cent.,  average  004  per  cent.  There  appears 
to  be  no  reason  to  think  that  these  small  quantities  can  have  any  appreciable 
effect  on  the  stability  of  explosives,  either  beneficial  or  otherwise. 

The  presence  of  these  substances  insoluble  in  water  is  not  confined  to  the 
first  runnings  :  there  is  almost  as  much  of  them  in  the  last  runnings,  and  even 
the  middle  fractions  contain  usually  0-02  to  004  per  cent.,  as  may  be  ascer- 
tained by  the  application  of  the  tests  just  mentioned. 

When  the  main  bulk  of  the  acetone  has  distilled  over,  the  temperature 
of  the  still-head  and  the  specific  gravity  of  the  distillate  commence  to  rise  : 
after  a  short  time  the  temperature  reaches  about  73-5°  and  the  specific  gravity 
0-840,  and  there  they  remain  steady  for  some  time.  The  distillate  now  con- 
sists almost  entirely  of  a  mixture  of  water  and  methyl-ethyl-ketone,  the 
next  homologue  to  acetone,  in  the  proportion  of  11-4  of  water  to  88-6  of  ketone. 
This  mixture  distils  unchanged,  and  the  water  can  only  be  separated  from  it 
by  treatment  with  a  dehydrating  agent  such  as  calcium  chloride  or  solid  caustic 
soda.  In  the  intermediate  fractions,  when  the  boiling-point  and  the  gravity 
are  rapidly  altering,  the  distillate  contains  much  impurity,  substances  insoluble 
in  water  and  perhaps  ethyl-alcohol.  Afterwards,  when  the  boiling-point 
becomes  constant,  the  constant  boiling  mixture  comes  over  in  a  state  of 
considerable,  purity.  Then  after  a  time  the  boiling-point  rises  again,  and 
a  distillate  is  obtained  which  still  separates  out  into  two  layers,  the  lighter 
of  which  consists  mostly  of  higher  ketones  with  a  small  proportion  of  water 
and  impurities,  and  the  lower  largely  of  water. 

Methyl-ethyl-ketone,  when  freed  from  water,  gelatinizes  gun-cotton  as 
well  as  acetone,  and  has  no  bad  effect  upon  it.  It  would  be  possible  to  add 
a  considerable  proportion  of  it  to  acetone  without  causing  it  to  fail  in  any 
of  the  usual  specification  tests,  but  it  is  more  usual  to  sell  it  separately  for 
denaturing  spirit  and  dissolving  resins.  The  heavier  acetone  oils  are  also 
used  for  making  lacquers,  etc.,  bu1  do  qo1  command  a  very  good  price. 

It  has  been   discovered   by    Fernbach   that  starch   can    he  submitted   to  a  Acetone  frc 
process  of  fermentation  whereby  it   is  converted  into  a  mixture  of  fusel  oil  starc 
and  acetone,  and  it  has  been  proposed  to  convert   the  fusel  oil  into  artificial 


EXPLOSIVES 


robber,  whilst  the  by-produi  I  purified  and  placed  on  the  market.1 

It  has  been  stated  that  bom  l<"'  parte  of  dry  potato  substance  a  yield  of  22 
parte  of  robber  and  14  of  acetone  can  be  obtain* 

Acetone  can  also  be  made  from  acetylene  and  this  method  has  been 
many  during  the  War.1  If  acetylene  he  led  into  sulphuric 
acid  of  about  44  pei  I  strength,  and  the  product  he  boiled  with  water, 
it  is  converted  into  aldehyde.3  The  chai  _  -  Iso  effected  by  se  _  the 
acetylene  through  boiling  sulphuric  acid  of  this  strength.  The  reaction  i> 
-  sted  by  the  presence  of  a  little  mercuric  oxide.4  The  aldehyde  may  then 
be  oxidized  to  acetic  acid,  which  is  converted  into  acetone  by  heating  barium 
or  calcium  acetate,  or  by  passing  the  vapour  over  heated  barium  oxide. 

As  but  little  of  the  solvent  is  allowed  to  remain  in  the  finished  powder, 
it  is  advisabli  I  is  much    -       ssible  in  order  that  it  may  be  used  again. 

Qsiderable  proportion  is  lost  during  the  operations  of  forming  the  dough 
into  cords,  strips,  tube-  or  flakes,  and  hitherto  there  has  been  little  attempt 
to  recover  this  portion,  as  the  difficulties  introduced  into  the  carrying  out 
of  the  operations  would  absorb  too  much  of  the  profit  on  the  n  It 

-     aly  from  the  drying  stoves  that  recovery  is  attempted  as  a  rule.     When 
the  x.lvent  is  ether-alcohol  difficulties  are  introduced  by  the  great  volatility 
of  the  ether  :    by  drawing  the  air  away  from  the  si    ves  Through  cooling 
only  alcohol  is  recovered  generally.     A  greater  bulk  of  condensate  can  be 
obtained  by  using  refrigerated  water  or  brine,  but  if  the  temperature  of  the 

-  be  reduced  much  below  0*  C.  there  is  danger  of  the  coils  being  choked 
with  ice.  In  the  manufacture  of  artificial  silk  by  Chardonnet's  process  attempts 
have  been  made  to  recover  the  solvent  by  passing  the  air  up  towers,  win 

robbed  with  a  mixture  of  sulphuric  acid  and  water  or  with  oil.  T.  <  han 
delon  proposes  to  use  the  chlorine,  bromine  or  nitro-derivativt  s  of  aliphatic 
or  aromatic  hydrocarbons  for  the  recovery  of  ether  and  alcohol  from  air.3 
In  Spain  sulphuric  acid  is  used.6  It  has  also  been  proposed  to  compress,  cool 
and  re-expand  the  air  in  a  regenerative  machine  as  is  done  in  Lindes  plant 
for  the  manufacture  of  liquid  air.  but  whether  recovery  of  the  solvent  by 
such  a  process  would  prove  remunerative  seems  doubtful.7 

At  the  French  Government  works  at  Saint-Medard  the  solvent  is  rec- 
from  Poudre  B  by  the  following  method  :    A  trolley  charged  with  strii  -     : 
powder  is  run  over  a  metal  chamber  ;   a  door  opens  in  the  top  of  the  chamber 
just  large  enough  for  the  trolley  to  pass  through  ;   it  is  let  down  and  the  door 


5  •    J'.rkn..  J.  S  Ind.,   1912,  p.  B16 ;       -     '    7"../..  June  . 

-  1".   I  ..   1 1  :  : ..hi.  Nature,  M  -   ,    1916,  p.   - 

J  Lagermark  and  Elterkow,  B>  r..   \%11 

4    Erdinann  and   K  898,  p.  48. 

22,    1912. 

S  v.   1913,  p.  !  "   "■•    Warden,  pp.   192-498, 


SOLVENTS  349 

is  closed,  and  the  vapours  of  alcohol  and  ether  are  given  off  in  the  air-tight 
chamber.  They  are  drawn  off  by  a  steady  current  of  air,  condensed  by 
refrigeration  and  collected.  When  the  drying  is  sufficient  the  trolley  is 
removed.     It   is  stated  that   the  recovery  is  satisfactory.1 

A  higher  yield  of  recovered  solvent  can  he  attained,  if  the  air  after  passing 
through  the  condenser  is  returned  to  the  stove,  so  that  it  passes  constantly 
round  a  closed  circuit.  The  evolution  of  solvent  is  rapid  at  first,  hut  becomes 
slower  and  slower  as  the  powder  gets  dryer  :  large-sized  powders  for  heavy 
ordnance  may  have  to  remain  in  the  stove  for  months,  during  the  greater 
part  of  which  time  the  quantity  of  solvent  vapour  given  off  is  hardly  appre- 
ciable. In  laying  out  works  it  is  advisable  to  place  a  few  stoves  fitted  with 
recovery  plant  near  the  press-houses,  so  that  the  powder  can  be  transferred 
to  them  expeditiously,  and  dried  there  for  a  few  days.  After  this  preliminary 
drying  the  powder  can  he  transferred  to  other  stoves  situated  at  a  distance, 
where  no  attempt  is  made  to  recover  the  solvent.  Where  considerable  quan- 
tities of  powder  of  large  size  are  made,  the  area  covered  with  stoves  may 
extend  over  many  acres,  and  to  connect  them  all  up  with  a  recovery  plant 
would  be  very  costly. 

For  the  recovery  of  acetone  from  cordite  and  other  materials  Robertson  Acetone 
and  Rintoul  have  taken  advantage  of  the  fact  that  the  vapour  is  very  readily  recovery- 
absorbed  by  a  solution  of  sodium  bisulphite,  with  which  it  forms  a  compound. 
(VHeO,  NaHSO;,.2  A  very  simple  and  satisfactory  method  has  been  worked 
out,  by  which  practically  the  whole  of  the  acetone  in  the  air  of  the  stove  is 
recovered  in  a  very  pure  condition.  The  air  is  drawn  away  from  the  stove 
through  wide  zinc  pipes  to  the  recovery  house  where  it  is  caused  to  pass  up 
a  series  of  towers,  down  which  a  30  per  cent,  solution  of  the  bisulphite  is  flow- 
ing. Towers  were  designed  specially  for  this  purpose,3  and  they  have  proved 
very  successful  not  only  for  this,  but  for  many  other  purposes  also,  such  as 
purifying  air  (see  Fig.  70),  as  they  afford  a  maximum  surface  of  contact  between 
the  air  and  the  liquid,  and  offer  a  minimum  of  resistance  to  the  passage  of 
the  former.  The  towers  are  square  in  section  and  lined  with  lead  :  inside 
there  are  frames,  which  are  wound  with  strands  of  wool  zig-zag  fashion.  At 
the  top  of  the  tower  each  strand  dips  into  a  trough,  which  is  kept  supplied 
with  bisulphite  solution.  The  to])  of  the  tower  is  closed  by  means  of  a  glass 
plate,  and  there  is  also  a  glass  window  near  the  bottom,  so  the  action  of  the 
tower  can  be  watched.  There  are,  of  course,  various  pumps  or  eggs  and 
tanks,  so  that  the  solution  can  be  raised  again  and  passed  down  the  same 
tower  again,  or  the  next  one  nearer  the  stove.  When  the  solution  is  nearly 
saturated  with  acetone  it  is  transferred  to  a  still,  where  it  is  simply  heated  to 

1  P.  et  N..   If,,   1912,  |).   1<)8. 

-   Eng.  Pat.  25,994  of  L901 ;    (J.S.   Pat.  723,31]   of  1903. 

3  Eng.  Pat.   25,993   of    1901. 


350 


EXPLOSIVES 


drive  the  acetone  off  again,  as  it  has  been  found  that  practically  the  whole 
of  the  acetone  can  be  distilled  off  before  the  bisulphite  begins  to  decompose. 


gf'fa  f-^UI 


»»*:»  M-.tT  —  (~ 


Fio.   Tii.     Scrubbing    Towers  (Robertson  and  Rintoul's  JV 


A  littl«-  sodium  carbonate  or  caustic  Boda  i-  added,  however,  to  diminish  the 
amounl  <>f  sulphur  dioxide  that  passes  over,  and  to  combine  with  any  free 
sulphurous  acid  that  has  been  formed  by  the  oxidation  of  the  bisulphite, 
and  the  consequent  formation  of  sodium  Bulphate.  The  crude  distillate  thus 
obtained  i-  mixed  with  water  and  a  little  sodium  carbonate,  and  distilled  again 
from  a  >till  Buch  a-  that  shown  in  Fig.  69.     It  i-  thus  obtained  in  an  extremely 


SOLVENTS 


351 


pure  state  ;    it  contains  no  detectable  quantity  of  any  impurity  except  some 
ethyl-methyl-ketone,  which  is  harmless,  and  a  trace  of  carbonic  acid.     The 


— 
- 
- 


to 
6 

O 


3 

o 


Per  Cent.  Acetone  by  Weight. 
o             to             10             i+o           ro             to            ?o             go            fa           /  o 

■00020 
•00016 
-00012 

00008 

00004 

too 


fO 


Zo 


/6  0 


i<*o  a 


o 
5 

So  < 

o 

S-i 

60      g 

0/ 

Ph 

u 

<*o     S 


Jo 


po  ro  tf<?  ^  *<j  Jo 

Per  CVnt.  Nitro-glycerine  by  Weight. 

Fig.  71.     Vapour  Pressures  uf  Mixtures  of  Acetone  and  Nitro-glycerine  at  18°  C. 


bisulphite  solution  is  prepared  by  passing  sulphur  dioxide  into  a  solution 
of  sodium  carbonate,  the  sulphur  dioxide  being  made  by  burning  sulphur 
in  a  small  burner  in  a  current  of  air. 

Another  reason  for  not  attempting  to  recover  the  acetone  from  the  last  Volatility  o 
stages  of  the  drying  of  a  nitro-glycerine  powder  is  that  nitro-glycerine  is  given  ^e  nifro" 
off  much  more  readily  when  the  greater  part  of  the  acetone  has  been  removed. 
Fig.  71  shows  how  rapidly  the  vapour  tension  of  the  nitro-glycerine  rises  when 
the  percentage  of  acetone  is  very  small.1     In  the  ease  of  cordite  the  problem 

1  Marshall,   Trans.   Chun.   Sue.    L906,   89,  p.    1350;    Proc.   1913,  p.    157. 


- 


EXPLOSIVES 


•mplicated  by  the  presence  of  gun-<  otto       »nd  the  vapour 
mixtures  of  gun-cotton  and  acetone  have  not  been  determined.     It  is  probable, 
however,  that  in  the  freshly  pressed  -        -        ntaining  a  fairly  large  percei.-    _ 
of  acetone,  a  considerable  proportion  of  it  is  dissolved  in  the  nit ro -glycerine, 
thus  reducing  the  vapour  pressure  of  the  latter,  but  when  the  pern 
acetone  has  been  reduced  to  a  small  amount  by  drying,  nearly  the  whole  of 

asolved  in  the  gun-cotton,  so  that  the  nitroglycerine  exerts  nearly  it- 
full  vapour  pressure.  The  result  of  this  is.  that  in  the  early  stages  of  the 
drying  there  is  little  or  no  danger  of  nitro-glycerine  being  deported  in  the 
pipes  leading  from  T:  to  the  recovery  house,  but  in  the  later  stages  it 

will  be  deposited.  Care  must  be  taken  therefore  in  laying  the  pipes  that  the 
nitroglycerine  will  only  accumulate  in  places  from  which  it  can  be  drawn  off. 
At  all  the  lowest  points  of  the  pipe-run  small  draining  tubes  must  be  provided  : 
these  can  be  closed  with  rubber  c  -  that  the  nitroglycerine  can  be  drawn 
off  daily  into  a  rubber  or  gutta-percha  bottle  or  beaker. 

Another  danger  that  has  to  be  guarded  against  is  the  communication  of 
fire  from  one  stove  to  another  through  the  pipe-lines.  In  Robertson  and 
RintouTs  system  protection  is  afforded  by  the  introduction  of  traps,  in  which 
fine  wire  gauze  is  interposed  to  prevent  the  further  travel  of  the  flame.  They 
are  so  arranged  that  a  gas  explosion  in  the  pipe  will  blow  out  a  disc  of  thin 
material  and  -so  relieve  the  pressure. 

-  not  only  in  the  pipe-lines  that  the  explosibility  of  mixtures  of  vapour 
and  air  has  to  be  guarded  against,  but  wherever  combustible  and  volatile 
liquids  are  used:  in  the  incorporating  and  press  ho  w  -  stoves,  magazines 
and  solvent  store-houses,  great  care  must  be  taken  that  no  flame  or  spark 
may  ignite  a  mixture  of  air  and  vapour.  The  following  Table  gives  the 
explosive  limits  for  a  number  of  volatile  liquids  as  determined  by  Kubierschky  :  1 


Percentages 

1  irr.e 

Per  cent,  by 

Weight 

_   ■ 

Lower  Limit 

Upper  L 

1  percent.  1 

B- nzene   ...                     .                  1-4 

4  7 

Toluene 

14 

— 

_ 

Ethyl -alcohol    . 

■ 

1  .,] 

■ .  jyl-aleohol  . 

(18 

1-12 

- 

— 

i    i 

Ether 

1-8 

_ 

Carbon  bisulphide 

4  1 

— 

.     • 

!'>•  nzine    . 

. 

(4-8) 

— 

1    ntane   . 

2  " 

(48) 

1  Aug.,   1801,  p.    130. 


SOLVENTS  353 

If  the  percentage  of  vapour  fall  below  the  lower  limit  or  rise  above  the  upper, 
the  mixture  is  no  longer  inflammable,  but  these  limits  depend  upon  the 
conditions  under  which  the  experiment  is  carried  out.     In  a  large  flask  the 

limits  are  wider  than  in  a  narrow  tube,  and  a  small  spark  often  will  not  ignite 
a  mixture  that  can  be  caused  to  explode  by  the  application  of  a  powerful  spark 
or  a  Maine.1  The  limits  are  much  narrowed  by  the  introduction  of  carbon 
dioxide  or  other  indifferent  gas.  It  has  been  shown  by  Olie  a  thai  the  intro- 
duction of  a  jet  of  steam  will  extinguish  a  large  quantity  of  fiercely  burning 
alcohol  in  a  few  minutes,  and  it  is  recommended  that  buildings  containing 
considerable  quantities  of  inflammable  liquids  be  fitted  up  bo  thai  a  fire  can  be 
extinguished  by  this  means.  It  must  not  be  forgotten  that  vapours  may  be 
ignited  by  electric  sparks  generated  by  the  friction  of  driving  belts,  and  pre- 
cautions should  be  taken  to  dissipate  any  charges  that  may  be  thus  formed. 

Even  the  empty  drums  which  have  contained  liquids  may  give  rise  to 
serious  accidents  if  the  last  traces  are  not  removed.  On  March  30,  1904,  a 
drum  that  had  contained  acetone  exploded,  killing  two  men  and  injuring 
several  others  at  Prince's  Dock.  Glasgow.  The  drums  when  emptied  should 
be  left  without  their  bungs  and  should  be  placed  upon  racks  in  the  open  for 
a  few  days  with  the  bungholes  downwards  :  if  at  the  end  of  that  time  it  is 
found  that  the  smell  of  the  solvent  is  still  perceptible  in  the  drum,  the  last 
traces  can  be  removed  by  directing  a  jet  of  compressed  air  into  the  drum  for 
a  minute  or  so,  relying  on  the  absence  of  smell  as  an  indication  that  the  removal 
is  complete.  The  bungs  should  then  be  replaced  and  screwed  up  so  tightly 
by  means  of  a  key  that  it  is  impossible  to  remove  them  by  hand,  or  for  them 
to  work  loose  during  transit.3 

The  vapours  of  many  of  the  liquids  used  as  solvents  are  injurious  to  the  Toxicity  of 
health  of  those  exposed  to  them.     Benzene  is  very  poisonous,  but  is  not  used  vapour9, 
much  for  making  smokeless  powders.     Acetone  has  no  very  serious  effect. 
That  of  the  alcohols  increases  with  the  molecular  weight  :    amyl-alcohol  is 
decidedly  the  worst  of  those  generally  used.     It  has  been  found  that   the 
following  doses  are  fatal  per  kg.  of  animal  :4 

Methyl-alcohol 6*00  g.  per  kg. 

Ethyl  ,,       (absolute)         .....  7-75      „       „ 

Propyl         ,,  .......  3-75      „       „ 

Butyl 185      „       „ 

Amyl 1-50      „ 

A  mixture  of  the  vapours  of  ether  and  alcohol  is  more  poisonous  than  that 
of  either  of  the  substances  separately.  For  this  reason  also  buildings  in  which 
amyl-alcohol  or  ether-alcohol  vapours  may  be  present  should  be  well  ventilated. 

1  See  also  Bunte,  J.  /.  Gash.,  1901,  p.  1835  ;   J.  Soc.  Chem.  Ind.,  1902,  p.  33. 
i  P.  ct  S.,   1."..   1910,  p.   160. 

3  A.B.,   1004,  p.  94.  <  P.  it  S.,  vol.  xvi.,   1912,  p.   128. 

VOL.  I.  23 


PART  VIII 

BLASTING  EXPLOSIVES 


CHAPTER  XXV 


NITROGLYCERINE  HIGH  EXPLOSIVES 

Kieselguhr  :  Manufacture  of  dynamite  :  Properties  of  dynamite  :  French 
dynamites  :  American  dynamite  :  Ligdyn  :  Ammonia  dynamite  :  Jndson 
powder:  Dynamite  Nbs.  2  and  3:  Gelatinized  explosives:  Boxes  for  jelly: 
Diminution  of  sensitiveness  and  stability  :  Exudation  :  Gelignite  :  Gelatine 
dynamite  :  Wrappers  :  40  per  cent,  dynamite  :  American  gelatin  dynamites  : 
Foreite :  French  gelatinized  explosives:  Low  freezing  explosives:  Safety 
explosives  containing  nitro-glycerine  :    Carbonites 

The  first  attempts  to  use  liquid  nitro-glycerine  for  blasting  proved  so  dis-  Kieseigui 
astrous,  that  it  became  necessary  to  find  some  means  of  converting  it  into 
a  solid,  unless  its  wonderful  power  was  to  be  lost  to  the  world.  Many  of 
the  principal  countries  had  indeed  passed  laws  forbidding  the  use  of  nitro- 
glycerine, when  in  1866  Nobel  discovered  that  it  could  be  rendered  compara- 
tively safe  by  absorbing  it  in  kieselguhr.  This  at  once  gave  a  great  impetus 
to  the  high  explosives  industry  and  laid  the  foundations  of  the  great  fortune, 
which  Nobel  afterwards  increased  by  other  inventions  and  by  his  financial 
ability.  Kieselguhr  or  guhr  is  a  fine  siliceous  earth  consisting  of  the  remains 
of  diatoms  and  other  microscopic  animals.  It  should  have  the  power  of 
absorbing  three  times  its  weight  of  nitro-glycerine,  and  should  be  free  from 
gri  1 1  y  |  >a  rticles.  It  is  found  in  the  Lunerburger  Heide,  to  the  north  of  Hanover, 
also  in  Austria,  Scotland,  Norway,  and  Australia.  The  following  analyses 
show  its  composition  : 


From  Oberlohe  (Hanover) 

Dried               Calcined 

Top  Stratum 

Second 
St  ratum 

(Gody) 

(Gody) 

(Sanford)             (Hagen) 

Silica  .... 
( lalcium  carbonate 
Lime  .... 
Magnesia 

Iron    oxide  . 

Alumina 

Organic    matter     . 

Moisture 

87-85 
•73 

•73 
•13 

2-28       | 
8-43 

74-48 
■34 

39 
24-42 

94-3                 96-34 

1  -64 
2-1 
1-3 

1") 
J            -4 
i         19 

357 


358  EXPLOSIVES 

A  sample  of  the  guhr  used  at  Ardeerin  1884  was  analysed  by  Dupr6(£..B.  61    : 

it  was  of  pale  red  colour  and  passed  entirely  through  a  20-mesh  sieve;    it 
consisted  of : 

Soluble  silica,  oxide  of  iron          .          .          .          .          .  .9* 

Insoluble  silica.   >ainl   and    m  it       .            .            .            .            .  .2-00 

L.  SB  on  ignition           .          .          .          .          .          .          .  .0-60 

Moisture               .          .          .          .          .          .          .          .  .       171 


100-00 


In  consequence  of  the  cessation  of  supplies  from  Germany  and  Austria 
Bteps  arc  being  taken  to  dew-lop  deposits  iii  Victoria  and  New  South  Wales. 
Those  at  Lillieur.  north-west  of  Ballarat,  are  said  to  be  suitable  for  the  manu- 
facture of  dynamite.1 

Guhr  is  decidedly  hygroscopic  and  cannot  be  dried  effectively  except  at  a 
high  temperature  :  it  is  necessary  to  calcine  it  at  a  l<»w  red  heat.  The  organic- 
matter  i-  thus  destroyed  also.  Sometimes,  however,  the  guhr  is  only  charred, 
in  which  case  a  considerable  percentage  of  carbonaceous  matter  will  remain. 
The  guhr  may  be  mixed  with  some  ochre,  mica,  talc  or  barium  sulphate  with- 
out impairing  it>  absorptive  powers.  Ochre  gives  the  dynamite  a  uniform 
red  colour.  Carbonate  of  ammonium,  sodium,  magnesium  or  calcium  is 
added  up  to  -  per  cent,  of  the  finished  explosive,  in  order  to  neutralize  the 
acid  formed  by  the  decomposition  of  the  nitro-glycerine  on  storage.  The 
carbonates  of  magnesium  and  calcium  are  best,  as  the  others  have  a  decom- 
posing  action  on  the  explosive. 

The  carbonate  and  other  additions  should  be  mixed  very  intimately  with 
the  guhr,  which  is  then  passed  through  a  30-mesh  sieve  to  remove  all  foreign 
bodies.  The  material  is  then  weighed  out  into  a  lead,  brass  or  copper-lined 
box,  or  a  rubber  bag,  and  nitro-glycerine  is  poured  on  in  the  proportion  of 
not  more  than  7.")  parts  by  weight  to  :_>:>  of  the  absorbent.  After  standing  for 
a  time  the  material  is  kneaded  or  mixed  by  hand  in  mucli  the  same  way  as 
i-  done  with  cordite  paste.  The  mixture  is  then  conveyed  to  a  cartridge 
hut  in  which  are  erected  two  to  four,  but  preferably  only  two.  cartridge 
machines.  Each  of  these  consists  of  a  brass  plunger  working  vertically 
through  two  sleeves  or  guides  (Pig.  72).  It  is  worked  by  means  of  a  hand- 
lever,  and  i-  -hod  at  the-  Lower  end  with  lignum  vita'  or  ivory.  This  lower 
end  works  in  a  thin  brass  tube  of  the  same  diameter  as  the-  finished  cartridge 
i-  t<»  be.  The  upper  end  of  the  tube  forms  the  apex  of  an  inverted  cone  or 
hopper  of  -oft  leather  mot  shown  in  the  illustration),  having  a  capacity  of 
about  a  pound  of  dynamite-,  the  Upper  edges  of  this  hopper  being  connected 
by  three  or  more  cords  to  a  boss  higher  up  on  the  plunger.  The-  plunger  works 
easily  through  the  guides  to  minimize  the  friction,  and  there  i-  .1  good 

1  Chem.  Trade  Journ.,  Maj    13,   1916,  p.  426, 


NITROGLYCERINE   HIGH   EXPLOSIVES 


359 


clearance  between  it  and  the  tube.  Sometimes  it  carries  an  inverted  bell 
to  prevent  the  explosive  working  ap  into  the  lower  guide.  To  work  the 
apparatus  a  girl  wraps  a  paper  cartridge  wrapper  round  the  outside  of  the 

tube,  leaving  sufficient  paper  at  the  bottom  to 
turn    in    and    close  the    end.       Holding   this  in 
position    with    one    hand    she    works    the    pump 
handle  with   the  other;    the  effect  of  each  up- 
ward stroke  is  to  jerk  the    soft   leather  hopper 
by  means  of  the  cords,  and  cause  the  contained 
dynamite  to    fall  into    the    tube,   whence    it  is 
forced  'by  the  ensuing    downward    Btroke  into 
the  paper  wrapper  at  the  lower  end 
of  this  tube  ;  this  is  repeated  until 
the    cartridge    is    of    the    required 
length,  when  it  is  removed,  and  the 
upper  end  of  the  paper  is  folded  in. 

The  operation  of  making  these  cartridges  is 

a  dangerous  one,  and  the  greatest  care  should 

be  taken  to  minimize  the  danger.1     There  should 

be  no  nails  in  the  machine  ;    the  mouth  of  the 

tube  should  be  bevelled  and  faced  with  leather 

so  fitted  that  an    untrue  plunger   cannot  strike 

the  edge  of  the  tube  :  the  diameter  of  the  body 

of  the  plunger   should  be   less  than    that  of  its 

working  end  :    and  the  tube  should  be  slightly 

conical   after  the   first  short  distance.     On   no 

account  should   any   attempt   be   made  to  work 

the  explosive  when  it  is  frozen,  and  work  should 

be  suspended  altogether  if  the  temperature  inside 

the  hut  is    below  50°.      Only  a    small  quantity 

of  explosive  should  be  allowed  in  the  hut  at  one 

time,  the  remainder  being  kept  in  a  cupboard 

outside.     The  huts  should  beat    least    40  yards 

one  from  another,   and    surrounded  with    good 

mounds. 

The  material  thus  made  is  a  plastic  mass  varying  in  colour  from  buff  to  Properties 

reddish    brown.     Direct    contact    with   water  causes   the   nitro-glycerine   toDynamite' 

separate  from  it  ;    therefore  great   care   must    be  exercised  when   u>ing  it   in 

wet    places.      It    freezes   BOmewhat    more   readily   than   liquid   nitro-glycerine. 

When   ignited   in  small  quantities  it   simply   hums  away  fiercely,   but    fatal 

accidents  have  arisen  in  considerable  number  from  persons  supposing  that, 

1  See  SLR..  61,  NTos.  14.".  and  184. 


Fig 


72.     Dynamite  Cartridge 
Machine. 


EXPLOSIVES 

as  it  i-  reasonably  safe  to  ignite  a  few  carta  unfrozen  dynamite,  it  i- 

equally  Bafe  to  warm  it  upon  a  shovel,  in  an  oven,  in  a  tin  over  a  fore,  or  in 
various  other  ways,  which  usually  lead  to  a  verdict  of  "Accidental  Death." 
Frozen  dynamite  i>  much  more  susceptible  to  explosion  by  simple  ignition. 
but  it  is  less  sensitive  to  detonation,  as  also  to  a  blow  or  friction  under  - 
conditions,  but  the  annals  of  explosives  are  full  of  instances  of  the  fatal 
unexpected  explosion  of  frozen  nitro-glycerine  explosives,  which  had  not 
been  treated  with  proper  respect.  Tlu-  density  of  dynamite  i<  stated  to  be 
1-4  to  1  .V  but  I  have  found  it  to  be  about  1»;2.  If  there  were  no  air  B] 
in  it  the  density  would  be  177.  The  temperature  of  ignition  i-  given  a-  182°. 
The  following  are  analyses  made  by  Dupre  in  1901  of  two  samples  from 
Ard<  •• 

Nitro-glycerine     ..... 

-elguhr  ...... 

Ammonium  carl'   ■     •  ... 

Other  soluble  matter  .... 

Moisture      ...... 


3       - 

73-9S 

. 

019 

0-16 

Oil 

0-24 

0-38 

. 

. 

II 

0-1 

015 

1      '    . 

0-61 

Containing  sand,  calculated  on  dynan 

Cieaelguhr 

Both  samples  were  of  a  light  brick  red  colour  and  gave  heat  te>ts  of  over 
thirty  minuu 

This  material  is  called  in  Great  Britain  Dynamite  No.  1.  or  Kieselguhr 
Dynamite,  or  simply  Dynamite,  and  in  Germany  the  nomenclature  is  much 
the  same,  but  in  America  it  i>  called  Giant  Powder,  and  the  term  dynamite 
i-  usually  applied  to  a   mixture  of  nitn    g  ine,  wood  pulp  and  sodium 

nitrate,  which  is  not  authorized  in  England  at  all.  Dynamite  No.  1  is  not 
made  very  extensively  now.  as  it  has  been  replaced  by  various  gelatinized  nitro- 
glycerine mixtures,  but  it  possesses  the  advantage  that  it  i>  more  stable  when 
stored  at  high  temperatures,  as  the  acid  products  of  decomposition  are  imme- 
diately neutralized  by  the  carbonate  present.  I  have  examined  dynamite 
that  had  been  Btored  for  a  considerable  number  of  years  at  Aden,  and  could 
tind  no  signs  of  instability,  when  -  gelatinized  explosive  under  the  same 
conditions  would  have  given  a  very  low  heat  test. 

lea  infusoria]  earth  other  siliceous  materials  have  been  used  for  the 
manufacture  of  dynamite  ;  in  France,  for  instance,  a  material  called  Randanite, 
which  is  found  in  Auvergne,  and  has  been  formed  by  the  weathering 
feldspar.  Berthelot  proposed  the  use  of  a  special  artificial  silica  made  by 
decomposing  silicon  fluoride  with  water  and  having  a  very  high  absorptive 
power.  Nobel,  in  hi>  patent  specifications,  mentioned  a  number  of  materials 
1  Chalon,  p.  302  ;    Vennin  >-i  I 


XlTRO-GIATERINE   HIGH   EXPLOSlVKs 


361 


such  as  powdered  brick,  dry  clay  and  plaster.  During  the  siege  of  Paris 
coal-ashes  were  used,  and  in  America  magnesium  carbonate  has  found  sonic 
favour. 

Formerly  a  number  of  special  mixtures  of  this  kind  were  made  in  France,1 
but  now  the  only  nitro-glycerine  explosive  with  inert  base  used  there  largely 
is  dynamite  No.  I  containing  75  per  cent,  of  nitro-glycerine  and  25  per  cent. 
of  guhr.  More  rarely  dynamites  Xos.  2  and  3  are  employed  containing  35 
and  25  per  cent,  of  nitro-glycerine  respectively.2  Dynamites  are  not  allowed 
to  be  transported  in  France  if  they  are  more  than  twelve  months  old.8 

As  nitro-glycerine  contains  an  excess  of  oxygen  even  after  all  the  carbon 
has  been  converted  into  dioxide,  the  idea  naturally  occurred  to  mix  it  with 
an  organic  absorbent  :  cork  charcoal  has  a  very  great  absorptive  power,  but 
the  material  that  has  been  used  most  is  wood  pidp.  The  "Atlas  Powders  " 
introduced  from  America  by  the  Fenians  in  1883  and  1884  for  their  criminal  American 
attempts  were  of  this  type.  Two  of  the  samples  analysed  by  Dupre  had  the  dynamite 
following  composition  : 


Nitro-glycerine  ....     29*8 
Wood  sawdust  slightly  chaired  in 

parts 63-8 

Moisture    .  .  .  .  .6*4 


Nitro-glycerine  .  .  •  7 1  '6 

Wood  sawdust  and  a  little  chalk   .      24-9 

Moist ure   .  .  .  .  .        :»•.") 


But  these  mixtures  contained  an  excess  of  oxidizable  matter.  It  is  more 
economical  to  add  another  oxygen  carrier.  In  America  sodium  nitrate  is 
used  very  extensively  for  this  purpose.  In  the  Bureau  of  Explosives  Report 
No.  2,  Beistle  gives  the  results  of  the  analysis  of  a  large  number  of  American 
dynamites,  which  are  summarized  in  the  following  Table  : 


Grade 


Nitro-glycerine       Wood  Pulp       Sodium  Nitrate        Moisture 


tin  per  cent. 

50 

40 

30       ., 


53-5-651 
49-3-501 
34-8-41-9 
29-7   32-5 


U-2-210 

11-6-13-4 
7-7-13-9 
7-9    10-2 


16-0-29-8 
32-6  33-8 
38-4  50-2 
52-6  60-1 


116-318 
1-97-2-00 
0-80-3-60 
109   1-69 


1 1  will  be  seen  1  hat  t  he  variations  in  composition  in  each  made  arc  considerable  ; 
the  figures  for  the  50  and  30  per  cent,  grades  are  based  on  two  analyses  each 
only,  but  those  for  the  other  grades  on  a  considerable  number.  .Many  of  the 
dynamites   evidently   contained   a    few    per   cent,    of   some   other   constituents 


1  See   1st   edition  of  tliis  work.  p.  2S1. 

-  Vennin  el   Chesneau,  |>.  363.     Set   also  I'. 

3  Vennin  «t   Chesneau.  p.  •-!,i~>. 


>t  >'..  vol.  wii. 


158. 


EXPLOSIVES 


undetermined,  l>ur  those  in  which  there  was  a  considerable  deficit  have  been 
excluded  from  the  above  summary.  The  following  are  two  examples  of 
American  4<»  per  cent,  dynamic 

Nitro-glycerine 

Wood-pulp    .... 
9  dram  nitrate 

[cram  carbonate 
Magnesium  carbonate 
Sodium  chloride 
Moisture        .... 

Hall  and  Howell  give  the  following  as  the  composition  of  typical  American 
"  straight  "  dynamites  :l 


Straight  dynamite 

Hercules 

.40 

40 

11-76 

11 

.      47-25 

1 

4.") 

1 

1 
2 

.     — 

_rt  h 

I .")  per 

cent. 

20  pe  r  25  per  30  per 
cent.   cent.  cent. 

.'!■")  ]>■•! 

cent. 

40  per  45  per 

e<-nt.    cent. 

50pei 

cent. 

55  per  60  pei 

cent.  cent. 

Nitro-glycerine 

( !ombustible  materia]  2 

3    Lram  nitrate 

<  ialcram  or  magnesium  carbonate 

15 
20 
64 

1 

20 
19 

60 

1 

25      30 

IS        17 

56      52 

1         1 

35 

16 

48 

I 

40      4.". 
15       14 

44       4ii 
1          1 

50 
14 
35 

1 

.",.-,       CO 

15       16 

29      23 

1         1 

LOO 

L00 

L00     100 

100 

L00     100 

100 

100     100 

A  similar  explosive  is  manufactured  in  South  Africa  under  the  name  of 
Ligdyn.     The  40  per  cent,  grade  has  the  composition  : 


Nitro-glycerine 
Wood -meal 
Sodium  nitrate 
Wheal   Sour    . 


40 

13 
15 

■> 


The  cartridges  are  made  in  the  Quinan  packing  machine,  which  works  on  the 
same  principle  a-*  the  hand  machine  shown  in  Pig.  72.  but  it  is  operated  by 
power,  and  makes  thirteen  t<>  fifteen  cartridges  at  one  time.  <»ii  January  ::. 
1913,  the  contents  of  one  of  these  machines  exploded  and  killed  nine  persons 
and  injured  two  others. 

In  America  Ammonia  Dynamites  are  also  made,  in  which  a  large  proportion 
of  the  oitro-glycerine  is  replaced  by  ammonium  nitrate. 


1   Bureau  of  Mines,  Bulletin  No.    18. 

osisting  of  wood-pulp,  Hour,  and  sulphur  for  grades  below   4"  pei  cent. 

pulp  only  for  <  »t  In  i 


wood- 


NITROGLYCERINE   HIOH    EXPLOSIVES 


363 


The  following  Table  shows  the  compositions  of  typical  ammonia  dynamites 
of  various  grades  x  : 


Strength 

30  per  rent. 

36  per  cent 

10  percent. 

.~>u  percent. 

00  per  (int 

Nitro-glycerine 

15 

20 

22 

27 

:}5 

Ammonium  nitrate. 

L5 

L5 

20 

25 

30 

Sodium   nitrate 

51 

48 

42 

36 

24 

Combustible  material  2     . 

18 

16 

L5 

11 

10 

Calcium  carbonate  or  zinc 

oxide 

1 

1 

1 

1 

1 

An  explosive  of  a.  somewhat  different  type,  which  is  also  used  extensively  Judson 
in  America,  is  Judson  Powder,  which  was  patented  in  1876  by  E.  Judson. 
This  is  made  with  percentages  of  nitro-glycerine  varying  from  5  to  2(i  per 
cent.     Judson  Powder  R.R.P.    has    the    composition  : 


or 


Nitro-glycerine 
Sodium  nit  pate 
Sulphur . 
Cannel  coal 


Nitro-glycerine 

Sulphur,  coal  and  resin 
Sodium  nitrate 


(A 
16 
15 


a 
35 
60 


The  sodium  nitrate  is  mixed  with  the  combustibles  and  the  mixture  is  heated 
beyond  the  melting  point  of  the  sulphur  and  resin.  The  slightly  porous  mass 
thus  formed  is  coated  with  nitro-glycerine,  which  accelerates  the  explosion 
of  the  mixture  and  so  makes  it  considerably  more  violent.3  It  is  really  a 
sort  of  crude  gunpowder  containing  a  little  nitro-glycerine.  It  is  fired  with 
a  priming  cartridge  of  dynamite. 

The  great  objection  to  these  mixtures  is  that  sodium  nitrate  is  decidedly 
deliquescent,  and  ammonium  nitrate  still  more  so  :  even  from  a  moderately 
dry  atmosphere  they  take  up  moisture  and  become  liquid,  and  the  solution 
thus  formed  displaces  the  nitro-glycerine  and  causes  it  to  exude,  thus  giving 
rise  to  a  very  serious  danger.  For  this  reason  such  explosives  have  not  been 
authorized  in  England.  It  is  noteworthy  that  for  the  work  on  the  Panama 
(anal,  in  which  many  millions  of  tons  of  dynamite  have  been  used,  the 
Isthmian  ('anal  Commission  only  accepted  explosives  containing   potassium 

1  Hall  and  Howell,  loc.  tit. 

2  Consisting  of  wood-pulp,  flour,  and  sulphur. 

3  Bureau  of   Mines,    Unlit  tin    Xo.   48,  p.    6. 


:;.;4 


EXPLOSIVES 


Dynamite 
Nos.  2  and  3. 


Gelatinized 
explosives. 


Manufacture. 


B 

1 

till 

4.V7 

141 

LOS 

21-6 

40-9 

:;«• 

— 

— 

1-9 

0-2 

10 

nitrate  and  five  from  sodium  nitrate,  ma l:ih  -ium  aalts  ami  other  impurities 
which  would  make  the  material  hygroscopic.  Two  samples  of  Atlas  Powder 
used  in  the  construction  of  the  Panama  ('anal  were  analysed  by  Stillman  and 
had  tin-  composition  : 

Nitroglycerin.-  ..... 

Wood-pulp     ...... 

Potassium   nitrate   ..... 

Magnesium  oxide    ..... 

Chalk 

Moisture  ...... 

The  early  demand  for  an  explosive  that  was  milder  and  slower  than 
Dynamite  No.  1  was  met  in  England  by  the  manufacture  of  Dynamite  No.  2, 
which  was  recommended  for  work  in  eoal-mines  and  quarries.  This  consisted 
of  not  more  than  18  per  cent,  of  nitro-glycerine  mixed  with  some  1<»  per  cent. 
of  charcoal  and  72  per  cent,  of  saltpetre,  and  Bometimes  a  little  paraffin.  It 
was  practically  gunpowder  in  which  nitro-glycerine  had  been  substituted  for 
sulphur.  Dynamite  No.  .3  was  a  more  powerful  explosive,  and  consisted  of 
a  mixture  of  equal  parts  of  kieselguhr  dynamite  and  a  mixture  of  saltpetre 
and  wood-meal. 

In  1875  Xobel  made  a  further  advance  of  the  very  first  importance  by 
hi-  discovery  that  by  dissolving  7  or  8  per  cent,  of  collodion  cotton  in  nitro- 
glycerine it  is  converted  into  a  gelatinous  -olid.  The  discovery  arose  from 
the  fact  that  Xobel  had  cut  his  finger  and  collodion  had  been  used  to  cover 
the  wound  :  whilst  the  inventor  was  experimenting  with  nitro-glycerine  some 
of  it  <_r<>t  mixed  with  the  collodion.  In  the  following  year  patents  were  granted 
in  the  principal  industrial  countries  protecting  the  invention,  but  it  was  some 
years  before  the  difficulties  of  manufacture  had  been  overcome.  In  Great 
Britain  the  manufacture  was  licensed  in  1878.  and  in  is  sit  the  manufacture 
was  commenced  on  a  large  scale  in  the  Continental  factories  of  the  Nobel 
Syndicate,  but  considerable  difficulty  was  found  in  fulfilling  the  requirements 
of  H.M.  Inspectors  of  Explosives.  The  first  products  exuded  nitro-glycerine. 
and  manufacture  was  suspended  for  -ohm-  year-  :  afterwards,  when  this 
difficulty  had  been  overcome,  the  blasting  gelatines  failed  to  pass  the  heat 
test .  and  it  was  not  until  1  *x7  that  the  manufacture  was  in  full  swing  in  Great 
Britain.  A  great  demand  for  the  material  sprang  up  at  once  in  consequence 
of  its  enormous  power  and  convenient  nature.  For  blasting  hard  rock  it  has 
proved  very  serviceable,  especially  when,  as  in  tunnelling,  it  is  not  necessary 
to  get  the  rock  out   in  large  pice,-. 

The  collodion  cotton  is  thoroughly  dried  and  reduced  to  a  tine  state  of 
division.  It  Bhould  not  contain  more  than  I  per  cent,  of  water.  A  weighed 
quantity  is  placed  in  a  brass-lined  box,  and  the  requisite  quantity  of  nitro- 


NITRO-CLYCKRINE   HIGH   EXPLOSIVES 


365 


glycerine  is  poured  on.  The  materials  arc  mixed  together  by  hand  and  allowed 
ti>  stand  for  some  hours  or  overnight.  The  box  is  then  taken  to  the  mixing 
house,  where  the  material  is  heated  to  about  50  C.  and  gently  mixed  until 
solution  is  complete,  which  takes  about  an  hour.  Al  tirst  the  mixing  was 
done  entirely  by  hand  with  wooden  stirrers,  hut  now  the  final  mixing  is  gener- 
ally performed  in  incorporating  machines  similar  to  those  used  in  the  manu- 
facture of  smokeless  powders  [set  Fiji's.  f><>,  57).  At  the  Ardeer  Factory  of 
Nobel's  Explosives  Co.  and  some  other  works  .MeRoberts's  machine  is  used 
(Fig.  73).  This  has  a  number  of  narrow  stirrer  blades  mounted  on  two  vertical 
spindles,  which  are  driven  from  above.  The  trough  containing  the  explosive 
mixture  is  wheeled  in  below  and  raised  by  means  of  suitable  gearing.  There 
are  stops  to  prevent  the  bottom  of  the  trough  coming  in  contact  with  the 
stirrers.     The  trough   has  a  double  wall,   through  which   hot   water  can  be 


Fjc.   7:i.     Plan  of  MeRoberts's  Incor- 
porator for  Blasting  Gelatine 


FlG.    74.      Cartridge  .Machine  for  Gelatinized 
Explosives 


circulated  from  a  tank  outside  the  building  maintained  at  a  temperature  of 
50°  C.  The  actual  temperature  of  the  mixture  is  40°  to  45°.  After  about  an 
hour  the  trough  is  removed  and  the  gelatine  is  allowed  to  stand  to  get  cool  and 
become  stirrer,  but  not  too  stiff.  In  1914  and  1915  two  severe  explosions 
occurred  in  the  mixing  houses  of  the  Nobel  Co.  at  Ardeer.  They  may  have 
been  caused  by  dropping  a  lead  apron  into  the  mixer.1  It  is  advisable  that 
the  machinery  be  not  running  whilst  the  trough  is  being  filled.  If  the  stirrers 
are  driven  electrically  there  should  be  an  automatic  cut-out  to  the  motor 
to  prevent   the  use  of  too  much  force. 

Starting  from  the  theory  that  blasting  gelatine  has  a  webbed  structure, 
\V.  A.  Hargreaves,  Inspector  of  Explosives  in  South  Australia,  has  arrived 
at  the  opinion  that  it  does  not  possess  sufficient  sensitiveness  unless  there 
be  a  considerable  amount  of  liquid  nitro -glycerine  between  the  webs.  He 
hence  concludes  that  the  gelatine  is  best  made  by  first  mixing  the  nitro-cotton 
thoroughly  in  the  cold  with  part  of  the  nit  ro-glycerine.  and  then  after  gelatin- 
ization  adding  the  rest  of  the  nitroglycerine.      It   is  claimed  that  in  this  way 

J  See  S.RR.  Nos.  209,  213, 


Reflected  light 


■  I 

#' 

- 


Transmitted    light 

Fig.  76.     Photographs  of  Blasting  Gelatines 
(From  Report  to  Parliament  of  \\  .   Australia   l.\    A.    K.   Mann) 


Fig.  7t>.     Photographs  of  Gelignites 
(From   Report   to  Parliament  of  W.  Australia  by  A.  E.  Mann) 


Fio.  77.     Photographs  of  South  African  Gelignites 
m   Reporl   to  Parliament  of  W,  Australia  by  A.   I"..  Mann) 


368  EXPLOSIVES 

blasting  gelatine  has  been  manufactured  which  is  less  liable  tit  her  to  become 
insensitive  or  on  the  other  hand  to  exude.1 

Blasting  gelatine  may  be  made  into  cartridges  in  the  machine  shown  in 
Fig.  '-.  or  the  "  sausage  machine  "  illustrated  in  Fig.  74  may  be  used  for  this 
and  other  gelatinous  explosives  that  are  not  too  stiff.  The  gelatine  is  fed  in 
through  the  hopper,  6,  whilst  the  handle  is  turned.  The  Archimedean  Bcrew 
forces  the  materia]  forward  and  out  of  the  nozzle,  the  diameter  of  which 
corresponds  with  the  size  of  cartridge  to  be  produced,  ft  is  necessary  that 
the  jelly  should  be  warm  during  this  operation,  as  otherwise  it  breaks  up. 
The  following  is  the  approximate  output  of  cartridges  of  gelignite,  gelatine 
dynamite  or  blasting  gelatine  in  a  day  of  To  hours  by  a  gang  of  four 
girls,  one  working  the  cartridge  machine  and  the  other  three  rolling  car- 
tridgi 

Size  of  cartridge  Output,  lb. 

t,   10 1,000 

|,    2 1,200 

1£,  4 1,500 

There  are  grooves  inside  the  body  to  prevent  the  material  rotating.  In  all 
machines  used  for  working  these  substances  it  is  essential  that  only  bronze 
or  other  suitable  alloy  be  used,  and  all  bearings  must  be  so  arranged  that 
the  nitro-glycerine  cannot  get  into  them.  When  the  nitro-glycerine  is  hot 
it  is  decidedly  more  sensitive  than  when  cold. 

The  boxes  for  conveying  the  mixture  of  nitro-glycerine  and  collodion  cotton 
are  usually  made  of  wood  lined  with  copper,  brass,  lead  or  rubber,  or  of  heavy 
copper  tinned  inside  and  provided  with  rubber  rims.  They  should  be  so 
constructed  as  to  prevent,  as  far  as  possible,  those  surfaces  which  are  liable 
to  have  explosive  on  them  from  coming  in  contact  with  one  another,  or  with 
the  supports  on  the  bogie  on  which  they  are  carried.  The  boxes  should  be 
cleaned  thoroughly  at  frequent  intervals.  An  explosion  that  occurred  at 
Arklow  on  August  4,  1911,  is  ascribed  to  the  neglect  of  these  precau- 
tions.9 

After  manufacture  blasting  gelatine  continues  to  stiffen  for  a  considerable 
time  and,  unfortunately,  as  it  gets  stiffer  it  becomes  less  sensitive  to  detonation, 
BO  that  old  blasting  gelatine  may  give  a  misstire.  Thus  Soddy  found  that 
gelatines  which  gave  results  of  r>7n  to  600  c.c.  in  the  lead  block  when  first 
tested,  after  keeping  for  a  year  gave  only  340  to  420  c.c.  when  fired  with  a 
No.  ''•  detonator,  but  gave  normal  results  again  when  a  No.  7  detonator  was 
used.'     Indeed,  it  is  not  easy  to  produce  a  collodion    cotton  which  has  the 

1  J.  Soc.  Ghem.  In, I.,  1914,  p.  :v.\l.  -  S.R.,  No.  201. 

3  A.  and  E.,   1912,  p.   22. 


NITROGLYCERINE   HIGH   EXPLOSIVES  369 

right  degree  of  gelatinizing  power  and  is  at  the  same  time  sufficiently  stable  and  stability 
to  stand  transport  through  the  tropics,  to  Australia,  for  instance.     In  1909 
125,000  lb.   of  gelignite   Mere  condemned   i.i    Western  Australia    alone    on 
chemical  grounds. 

Diminution  of  sensitiveness  of  the  gelatine  is  accompanied  by  in- 
crease of  stiffness,  but  the  reason  of  these  changes  is  not  well  under- 
stood. Hargreavess  theory  has  been  mentioned  above,  but  it  is  not  by 
any  means  certain  that  a  gel  such  as  blasting  gelatine  has  a  webbed  or 
cellular  structure.  The  alteration  must  of  course  be  due  to  some  change 
in  the  structure  of  the  particles,  but  there  is  no  direct  evidence  to  show 
what  this  structure  is.  It  is,  however,  a  general  property  of  gels  to  set 
slowly  and  stiffen  gradually  when  cooled  again  after  being  heated  and 
the  longer  and  stronger  the  heating,  the  slower  is  the  setting  in  many 
instances.  The  heating  causes  a  diminution  in  the  size  of  the  particles 
and  prolonged  storage  in  the  cold  may  produce  the  reverse  change  The 
stiffening  may  therefore  be  due  to  increase  in  the  size  of  the  particles 
or  it  may  be  due  to  more  perfect  absorption  or  adsorption  of  the  nitro- 
glycerine. 

When  a  colloid  swells  up  by  imbibition  of  a  liquid  it  can  be  made  to  exert  Exudation, 
great  pressure  on  the  walls  of  the  containing  vessel.  Conversely,  if  sufficient 
Pressure  be  applied  under  such  conditions  that  the  liquid  can  escape  part  of 
it  will  be  expressed  until  equilibrium  is  again  established.  This  shows  that 
the  imbibition  is  a  reversible  process,  but  does  not  throw  much  light  other- 
wise on  the  process.  The  pressure  required  is  small  when  the  gel  is  very 
swollen.  Some  blasting  gelatines  require  so  little  pressure  to  deprive  them 
of  some  of  their  nitro-glycerine  that  the  weight  of  the  cartridges  is  sufficient 
to  cause  some  of  it  to  exude  into,  or  even  through,  the  wrapper  of  vegetable 
parchment. 

Blasting  gelatine  may  contain  anything  up  to   12  per  cent,  of  collodion 
cotton,  but  usually  7  or  8  per  cent,     To  increase  its  stability  1  or  2  per  cent 
of  calcium  or  magnesium  carbonate  may  be  added,  or  a  fraction  of  a  per  cent 
of  vaseline. 

For  most  purposes  blasting  gelatine  is  considered  too  expensive  and  is  Gelignite 
too  violent  and  local  m  its  action,  and  consequently  explosives  arc  used  in 
which  it  is  rendered  milder  by  the  addition  of  other  materials.  Gelignite  is 
an  explosive  which  is  very  largely  employed  :  il  consists  of  56  to  63  per  cent 
of  nitro-glycerine  thickened  with  oitro-cotton  to  a  thin  jelly  and  mixed  with 
potassium  nitrate  and  wood-meal,  with  the  addition  sometimes  of  calcium 
carbonate  or  mineral  jelly. 

Gelatine  dynamite  is  a  mixture  very  similar  to  gelignite  except   that  it  Gelatine 
contains  a  larger  proportion  of  blasting  gelatine  :    there  may  be  from  To  to  dynamUe' 
77  per  cent,  of  nitro-glycerine  in  it. 

VOL.    I. 

24 


370 


KXPLOSIYKS 


The  following  Table  shows  typical  compositions  for  these  three  standard 
gelatinized  explosives  : 


Forty  per  cent, 
dynamite. 


, ,.        •         , ,    ,    .  •                     <  libit  mi-                            ,    .. 

Blasting  Gelatine          ,, yili(IIlill.                 Gelignite 

Nitro-glycerine. 

Collodion  cotton 

Wood-meal         .... 

Potassium  nitrate 

Calcium  carbonate 

Moisture  ..... 

91  S 

8 

0-2 

74-5 
5-5 
4 

(••2 

60-5 

4-5 
7 
27 
0-2 
0-8 

The  wood  meal  used  for  the  manufacture  of  these  explosives  should  not  be 
too  fine,  otherwise  there  is  difficulty  in  obtaining  complete  detonation.  In 
some  factories  it  is  only  sifted  through  a  mesh  of  eight  holes  to  the  lineal 
inch,  but  in  other  factories  it  is  finer.  Apparently  the  air  vesicles  in  the 
coarse  meal  assist  the  detonation,  and  at  the  same  time  reduce  the  density 
of  the  explosive.  The  saltpetre  and  other  ingredients,  if  any,  are  ground 
more  iinely,  to  pass  a  50-  or  100-mesh  sieve.  The  mixture  should  contain 
sufficient  oxygen  to  convert  the  whole  of  the  carbon  present  into  carbon 
dioxide,  so  that  none  of  the  poisonous  carbon  monoxide  shall  be  formed  to 
foul  the  air  in  mines.  It  has  been  shown  by  Mann  (Report  to  the  Western 
Australian  Parliament,  1911)  that  if  the  paper  wrappings  on  the  cartridges 
are  removed  veiv  little  carbon  monoxide  is  formed  ;  not  more  than  2  per  cent, 
of  the  carbon  is  converted  into  this  gas,  but  with  the  wrappers  on  from  7  to  14 
per  cent,  is  formed.  In  Great  Britain  Wrappers  of  parchment  paper  are  used, 
but  on  the  (  out  incut  and  in  America  they  are  often  of  paraffined  paper.  A  wrap- 
ping of  metal  foil  would  have  far  less  reducing  action,  but  the  finely  divided 
metallic  oxide  would  itself  have  a  poisonous  action.  Impregnation  of  the  paper 
with  nitrates  or  similar  means  would  make  the  cartridges  considerably  more 
inflammable.  For  the  avoidance  of  this  danger  of  poisoning  with  carbon  mon- 
oxide the  most  effective  means  is  undoubtedly  efficient  ventilation  of  the  mines. 
Dynamite  No.  4  or  40  per  cent,  dynamite  is  a  somewhat  similar  mixture  : 
il  contains  not  more  than  39-5  per  cent,  of  nitro-glycerine  gelatinized  with 
not  less  than  0*75  per  cent,  of  nitro-cotton  and  mixed  with  sodium  nitrate 
and  not  less  than  16-5  per  cent,  of  dry  wood-meal  and  a  little  magnesium 
carbonate.  It  is  sometimes  sold  under  the  name  of  "  Parmer's  Dynamite" 
for  breaking  up  sub-soil,  making  holes  for  trees  and  other  agricultural  pur- 
poses, for  which  an  inexpensive  explosive  is  required.  It  differs  from  the 
ordinary  American  40  per  cent,  dynamite  in  that  the  nitro-glycerine  is  gelatin- 


NITRO-GLYCERINE   HIGH   EXPLOSIVES 


371 


ized  and  a  larger  proportion  of  wood-meal  is  used  :    the  danger  of  exudation 
is  thus  greatly  reduced. 

In  America  these  explosives  are  called  "  gelatins  "  or  gelatin  dynamites  ;  American 
according  to  Hall  and  Howell  J  they  generally  have  compositions  approximating  felatmt 
to  the  following  : 


30  per 

:;:>  per 

40  per 

50  per 

55  per 

60  per 

70  per 

Ingredients. 

cent. 

cent. 

cent. 

cent. 

cent. 

cent. 

cent. 

strength 

strength 

strength 

strength 

strength 

strength 

strength 

Nitro-glycerine   . 

230 

28-0 

330 

420 

460 

50  0 

60  0 

Nitro-cellulose     . 

0-7 

0-9 

10 

1-5 

1-7 

1-9 

2-4 

Sodium  nitrate  . 

62-3 

581 

52  0 

45-5 

42-3 

38-1 

29-6 

Combust  Lble  material ' 

'        L30 

120 

130 

100 

90 

90 

7-0 

Calcium  carbonate 

10 

10 

10 

10 

10 

10 

10 

!  looo 

1000 

1000 

100  0 

100  0 

1000 

100  0 

A  sample  of  40  per  cent,  gelatine  dynamite  analysed  by  W.  C.  Cope  was  found 
to  contain  : 


Nitro-glycerine 
Nitro-cellulose 

Sodium  nitrate 
Wood -meal 
Sulphur 

Zinc   oxide    . 
Moisture 


30-70 
0-88 

54-27 
8-58 
308 
102 
1-47 

10000 


To  prevent  the  formation  of  poisonous  gaseous  products  of  explosion  Munroe 
and  Hall  advise  the  omission  of  the  sulphur.3  They  recommend  the  follow- 
ing as  a  well  balanced  formula  : 


Nitro-glycerine 

Nit  ro-cellulose 

Sodium  nitrate 

Flour 

<  !a  Icium  carbonal  e 


33 

1 

.".4 
11 

1 


100 


1  Bureau  of  Mines,  Bulletin    L8. 

2  Wood-pulp  is  used  in  60  and  in  70  per  cent,  strength  gelatine  dynamite.     Sulphur, 

flour,  wood-pulp,  and  sometimes  resin  are  used  in  other  grades.  Some  manufacturers 
replace  a  small  percentage  of  the  nitro-glycerine  in  these  grades  with  an  equal  amount 
of  ammonium  nitrate.     This  replacement,  however,  offers  little,  if  any,  advantage  other 

than   reducing  the  cost  of  manufacture.        3   Bureau  of  -Mines.   Hull,  tin   Xo.   80,  p.   11. 


72 


EXPLOSIVES 


¥::::■-. 


Low-i; 

explosives. 


The  nan  rcite "  is  al-o  emplo  :»r  ordinary  <:elkrnites 

containing  potassium  or  sodium  nitrate  and  wood-meal.  but  sometii 
for  mixtures  in  various  proportions    of    a    thin    bla-ting    gelatine  with  an 
:  bent  having  the  composition  : 

Sodium  nitrate  ........      ~ 

Sulphur 

Wood-tar 

Wood-pulp  ........        1 

In  Belgium  Forcites  were  manufactured  at  Baelen-snr-Netlie,  having  the 
following  composition 


Extra 

Superieur 

No.  1 

N      2 

Xitro-glyeerine 

64 

64 

4'.' 

36 

Nitro-cellulos> 

" 

3 

_ 

3 

Sodium  nitrate 

— 

24 

36 

Ammonium  nit  rat* 

_■ 

— ■ 

— 

— 

Wood -meal. 

6-5 

8 

13 

11 

Magnesia      .... 

1 

1 

— 

1 

Rye-bran     .... 

14 

They  are  also  made  with  corresponding  percentages  of       bassram  nitrate. 

In  France  ex  -  containing  mtro -glycerine  are  excepted  from  the  State 

monopoly  :   a  large  number  of  different  composition-  have  been  authorized  for 
manufacture  in  the  priva*  s.    The  following  a  examples  (Chalon) :  * 


Dynamite-gomme                          Gelatine 

Geli_ 

Extra 

f..rte 

Potasse     Soude       A 

B- 

B-            E 
soude 

Xitro-glyeerine  . 
Xitro-eellulose   .                   8-7 
Potassium  nitrate 
3     limn  nitrate. 
Wood-meal                             : — 

IT 

82-83     82-83     64 
6-5          6-5          3 
9-10        —        — 

_ 
8 

- 
- 

8 

57            49 
3 

1" 
—            3 

58 

2 

28 

Any  of  the  nitro-glycerine  explosives  can  be  made  with  low-freezing  nitro- 
glycerin- \V[  .     The  methods  of  incorporating  the  exploc 
are  the                    if  ordinary  nitro-glyceine  were  used.     In  England,  where 


1  Vermin  et  Ch«->neau,  p.  369.     See  also  Chalon,  p.  2 
-     tzerland  aee  B.  '/.-■  hokke,  8JS.,      •  9,  pp.  143,  144. 


For  similar  explosives  made 


NITROGLYCERINE   HIGH   EXPLOSIVES 


373 


the  winters  are  not  so  very  severe,  reliance  is  placed  rather  on  keeping  the 
magazines  warm  than  on  making  additions  to  the  explosive  mixtures,  but 
on  the  Continent  and  in  America  a  considerable  number  of  such  explosives 
are  in  use.  In  Germany  and  Switzerland  several  "  special  "  blasting  gelatines 
and  gelignites  are  made  containing  a  percentage  of  liquid  nitro-toluene  or 
other  nitro-aromatic  compounds,  or  glycerine  esters.  In  Austria  the  follow- 
ing are  manufactured  : 


Nitro-glycerine 
Nitrocellulose 

Nit  rn-toluene 
Wood-meal 

Rye  flour  . 
Sodium  nitrate 
Lamp-black 
Caput   mortunm. 
Sodium  carbonate 


Dynamit   1 
Bchwerfrierbar 

55 

2 

10 

8 

24 

0-5 
0-5 


The  following  is  a  French  explosive  of  this  class  : 

Nitro-glycerine 

Xitro-glycol  . 
Nitro-cotton 
Potassium  nitrate 
Wood  meal    . 


Dynamit  II 
Bchwerfrierbar 

38-5 

1-5 

8 

416 

312 
43-68 

0-52 

0-52 


66-4 

16-6 

5 
10 

2 


In  America  low-freezing  dynamites  are  made  which  differ  from  the  corre- 
sponding "  straight  "  dynamites  in  that  about  a  quarter  of  the  nitro- glycerine 
is  replaced  by  nitro-substitution  compounds.1  The  Red  Cross  dynamites 
made  by  the  E.I.  du  Pont  de  Nemours  Co.  are  explosives  of  this  class. 

The  following  are  the  compositions  of  typical  low-freezing  dynamites  as 
given  by  C.  E.  Munroe  and  C.  Hall  :  2 


Strength 

30  per 

35  per 

40  per 

45  per 

50  per 

56  per 

(50  per 

rent. 

cent. 

cent. 

cent. 

cent. 

cent. 

a  'lit. 

Nitro -glycerine     .... 

23 

26 

30 

34 

38 

41 

45 

Nitro-suhstitution  compounds 

7 

9 

10 

11 

12 

1  I 

15 

Combustible  material   . 

17 

lti 

15 

14 

1  » 

15 

in 

Sodium  nitrate     .... 

52 

48 

44 

40 

35 

29 

23 

Calcium  or   magnesium  carbonate. 

1 

1 

1 

1 

1 

1 

1 

The  composition  of  the  combustible  material  is  similar  to  that    in    the  corre- 
sponding "•straight"  dynamites. 

1  See  Hall  and  Howell,  Bureau  of  Mines,  Butt.  48,  p.  7. 

8  Bureau  of   Mine.,    Hull,  tin    No.   Si),   p.   22. 


374 


EXPLOSIVES 


The  use  of  these  low-freezing   i  -     ■  erine  explosives  diminishes  the 

danger  of  solidification,  but  does  not  01  it  entirely.     If  the  weather 

he  very  cold  it  is  still  i  re  to  make  use  of  thaw-houses  and 

warming-pans  to  prevent  accident. 

There  are  a  number  of  explosives  made  which  consi-t  practically  of  gelignite 

in  which  part  of  the  potassium  nitrate  lias  been  replaced  by  ammoninm- 

or    a    compound    containing    much    water    of    crystallization    such 

m    sulphate,    -        i  to    alow   down    the   explosion   and    reduce 

the  temperature  of  the  flame.     These  are  mostly  used  for  blasting  coal.     The 

•  d  of  all  the  "  Permitted  Explosive-  "  in  Great  Britain  was 

at  one  time  Saxonite.  made  by  Nobel's  Explosives  Co.     The  consumption 

in  1907  under  the  Coal-Mines  Regulation  Act  was  1,721,193  lb.     But  in  1909 

it  failed  when  re-tested  in  the  testing  gallery  and  was  removed  from  the  list. 

It  was  promptly  replaced  b\    S  nite.  in  which  the  limits  of  composition 

are  considerably  narrower,  and  of  which   1,071,143  lb.  were  used  in    1910. 

-  --  D    -    L,  however,  where  permitted  exploe  aot  compulsory, 

and  in  1911  the  consumption  was   135,548  lb. 


nit  • 

.sonite 

Nitroglycerine                               .                     .42-5-62 

51    -60 

Xitro-cotton  . 

2-5-  5 

3-4 

-ium  nitrate  . 

.      16    -27-1 

17    -19 

Wood-meal     . 

3-5-  8 

-  7 

Chalk    . 

. 

- 

Ammonium  oxalate 

. 

L2  5-14-5 

ire 

0    -   1-5 

Whilst  the  "  Woolwich  Test  "  was  in  force  a  number  of  other  explosives  very 
similar  I     S       -   nite  were  on  the  Permitted  List  :    Arkite,  Rippite,  Stowite. 
nigh  IV.  Swalite,  amongst 

To  pas-  the  more  severe  "  Rotherham  Test  '"  it  has  been  found  nee- 
to  reduce  the  percentage  of  nitroglycerine  and  increase  the  amount  of  nitrate 
and  oxalate.     The  following  are  <>n  the  Permitted  List  :  1 

Nil       -        rine 

Xitro-cotton    . 

m  nitrate 
-     lium  nit; 
Wood-meal 

nionium  oxa". 
- 1  are 
Maximum  charge,  oz. 
Power  (swing  of  bal.  pend.) 

1  In  the  Explosive*  m   Coal  Mints  Orders  the  limits  of  •  .-n  are  published. 

stated,  the  wood-meal,  <-t<-..  being  given  in  the 
"natural  dry  ith  about    10  per  cent,  of  store. 


No.  2 

Uuxite 

. 

32 

1 

1 

2~ 

— 

— 

28 

1<' 

]«' 

_ 

4" 

12 

2-41' 

2-45 

NITROGLYCERINE  HIGH  EXPLOSIVES 


375 


The  following  have  passed  the  Belgian  test  and  are  on  the  list  of  "  explosifs 
S.G.P."  : 


Dynainitc 

Grisoutite 

antigrisoutcusc  V. 

Nitroglycerine   .           .           .           .44 

44 

Cellulose 12 

12 

Sodium  sulphate           .           .           .44 

— 

Magnesium  sulphate  .          .          .     — 

44 

Charge  limit  e      ....    (>50  g. 

300  g. 

Equivalent,  dynamite  No.  1        .    .'!.">•> 

170 

There  is  also  Grisoutine  II,  which  is  practically  the  same  as  Dynamite  Anti- 
grisouteuse  V. 

One  of  the  earliest  and  most  successful  safety  explosives  was  Carbonite,  Carbonite. 
which  was  made  by  Bichel  and  Schmidt  first  about  1885,  and  after  under- 
going some  modifications  gave  satisfactory  results  at  the  Neunkirchen  test- 
ing station  in  1887.  It  consists  of  nitro-glycerine,  about  25  per  cent., 
absorbed  in  wood-meal  and  mixed  with  nitrates.  The  proportion  of  wood- 
meal  is  so  high  that  a  large  proportion  of  the  carbon  is  only  oxidized  to 
monoxide  : 


Nitro-glycerine 
Potassium  nitrate 
Barium  nitrate 
Wood -meal 
Soda 


25 
30-5 

4 
40 

0-5 


The  composition  lias  been  varied  by  the  substitution  of  other  nitrates  for 
those  mentioned,  and  of  rye  starch  and  other  carbo-hydrates  for  wood-meal. 
The  composition  has  been  imitated  by  many  other  manufacturers.  The 
following  are  some  of  the  explosives  of  this  type  that  passed  the  Woolwich 
test  : 


Carbonite 

Tutol 

Knlax 

Nitro-glycerine. 

26 

25 

25 

Potassium  nitrate 

}      -       i 

33 

26 

Barium   nitrate 

2 

5 

Wood-meal 

40  • 

40 

34 

Starch 

— 

— 

10 

Sulphurel ted   benzene 

1 

— 

- — 

Calcium  carbonate     . 

}        *      { 

— 

— 

Sodium  carbonate 

— 

— 

Sodium  bicarbonate  . 

i 

i 

376 


EXPLOSIVES 


There  are  a   Dumber  of  explosives  of  this  type  on   the  Belgian  li-t   of 
exploafa  S.G.P."  : 


Kol  . 
carl  >■ 

Minite 

Antipl  de  Surete 

Nitro-gTj -ci-!  in.-    . 

25 

25 

Nitro-g            in'  . 

- 

SSIUm    llHiaO* 

34 

.".."i 

Sodium  nitrate  . 

- 

Barium  nitrate  . 

1 

— 

Dinitro-toluene  . 

15 

Flour 

- 

Ammonium  sulphate  . 

G 

Tan-meal   . 

1 

— 

Cellulose       .... 

35 

Soda. 

0-5 

0-5 

Wood-meal 

35 

( lharge  limite    . 

-. 

750 

Charge  limit) 

<.t(MI 

Kijuix  ali-iiT 

501 

405 

Kt|ui\al»iit 

524 

Minerite  and  Colinite  antigrisouteuse  have  tin-  same  composition  as  Kohlen- 
carbonite,  and  Securophore  III  only  differs  from  it  in  having  1  per  vent,  wood- 
meal  instead  of  tan-meal  :  its  "  charge  limite  "  is  B50  grams,  equivalent  to 
548  grams  Dynamite  No.  1.     [ngelite  is  identical  with  Antigel  de  soi 

To  pass  the  Rotherham  test   it   has  been  found  necessary  to  add  a  cooling 
agent    such   as  ammonium  oxalate  : 


S    :  •■  r-K 

•  lax 

Cambrite 

N      2. 

No.  1 

I 

Nitro-gryoerine. 

23 

_~ 

J  4 

Collodion  cotton 

— 

— 

1 

— 

temum  nitrate 

27 

25-5 

16-5 

30 

Barium  nitrate 

3  5 

.". 

•"' 

— 

\V L-meal        .... 

:;s 

30 

31 

38 

81  irch      ..... 

— 

- 

— 

Ammonium  oxalate 

^ 

7 

8 

<  alcium  carbonate 

0-5 

— 

— 

— 

Maximum  charge,  oz. 

30 

30 

32 

24 

Power  (swing  of  bal.  pendulum,  inches 

)           L-98 

2*10 

2-21 

_ 

Sonic  ammonium  nitrate  explosives  also  have  a  small  percentage  of  nitro- 
glycerine added  to  render  them  less  insensitive,  and  to  make  it  possible  to  com- 
press them  to  a  higher  density  without  making  them  t<><>  difficult  to  detonate. 
These   are   dealt   with   in   Chapter  XXVII.     The  potassium  perchlorau 
plosives  dealt  with  in  Chapter  X.WI  also  generally  contain  mtro-glyoeriiie. 


Augendre 
.      50 

Pohl 

4!' 

Reveley 
48 

.      25 

28 

29 

.      25 

23 

23 

CHAPTER   XXVI 
CHLORATE  EXPLOSIVES 

Chlorate  dangers  :  Sprengel  explosives  :  Promethee  or  03  :  Rack-a-rock  : 
Cheddite  :  Steelite  :  Silesia  :  Potassium  perchlorate  explosives  :  Permonite  : 
Alkalsit  :     Polarite  :       M.B.    powder  :     Ammonium     perchlorate     explosives  : 

Yonckite  :  Blast  hie 

The  substitution  of  potassium  chlorate  for  saltpetre  in  an  explosive  mixture  chlorate 
increases  its  power  and   violence,    but   also   it-   sensitiveness.     A    favourite  dan*ers- 
mixture  has  been  "white  gunpowder,"  for  which  the  following  proportions 
have  been  recommended  : 

Potassium  chlorate        . 

Potassium  ferrocyanide  .... 

Sugar.  ....... 

Mixtures  of  chlorate  and  sulphur  or  a  sulphide  are  specially  sensitive.  Hence 
the  early  attempts  to  make  gunpowder  with  chlorate  led  to  disaster.  Such 
mixtures  are  used  for  percussion'  caps,  and  for  other  purposes  where  a 
high  sensitiveness  is  required.  They  have  also  been  used  for  the  manufacture 
of  coloured  lights  and  other  similar  fire-works,  but  in  England  this  is  now 
forbidden.  Means  have  been  found,  however,  to  make  blasting  explosives 
containing  chlorate,  which  are  not  more  dangerous  than  other  explosives. 
The  perchlorates  are  much  less  sensitive  than  the  chlorates,  and  as  they  are 
now  manufactured  at  moderate  costs,  their  use  in  explosives  is  extending 
rapidly.  Mixtures  containing  sodium  chlorate  are  more  dangerous  than 
those  containing  potassium  chlorate.1 

Under  ordinary  circumstances  chlorate  of  potash,  when  unmixed  with 
combustible  matter,  is  not  dangerous,  but  on  May  12,  1899,  a  large  quantity 
of  it  exploded  during  the  progress  of  a  tire  at  the  works  of  the  United  Alkali 
Co.  at  St.  Helens,  and  did  an  enormous  amount  of  damage.2  This  led  to  a 
more  thorough  examination  of  the  behaviour  of  potassium  chlorate  when 
heated.     Berthelot*  showed  that  if  it  be  subjected  to  a  blow  combined  with 

1  See  A.R.,  1904,  p.  28.  -    SLR.,  No.    L35. 

3  P.  ,t  >-.,  vol.  x..  1900,  p.  280;    Compt.   /.'.,../..   1899,  vol.   129,  p.  926. 

377 


EXPLOSIVES 

sudden  intense  heat  it  explodes;    he  devised  the  following  experiment:    A 
25  to  33  mm.  in  diameter,  closed  at  one  end,  Lb  supported  in  a  nearly 

vertical  position,  and  heated  in  the  flame  of  a  large  gas-burner,  until  the 
lower  part  has  attained  a  perceptible  red  heat.     A  glass  rod  i>  drawn  out  to 

the  thickness  of  a  coarse  thread,  thru  introduced  into  a  quantity  of  pure 
potassium  chlorate,  which  ha-  been  melted  in  a  porcelain  crucible,  withdrawn 
and  allowed  to  cool  until  the  salt  begins  to  solidify.  The  operation  is  repeated 
ral  times  until  a  few  decigrammes  of  solidified  -alt  are  accumulated  in  the 
form  of  an  oval  lump  on  the  end  of  the  glass  thread.  When  the  glass  tube 
i-  quite  led.  the  glass  rod  i-  introduced  until  the  potassium  chlorate  i-  within 
about  1<»  mm.  of  the  bottom,  care  being  taken  that  it  does  not  touch  the  tube 
anywhere.  After  a  short  time  the  chlorate  melts  and  falls,  drop  by  drop,  on 
to  the  red-hot  bottom  of  the  tube.  Each  drop  explodes  at  the  Instant  that 
it  come-  in  contact  with  the  glass,  producing  a  very  distinct  sound  and  a 
cloud  of  white  smoke. 

Dupie1  Bhowed  that  heat  alone  Buffices  to  explode  the  chlorate,  if  it  be 
applied  with  sufficient  suddenness.  A  bead  of  potassium  chlorate,  supported 
in  a  loop  of  thin  platinum  wire,  can  be  made  to  explode  by  heating  it  rapidly 
either  in  a  gas  flame  or  by  means  of  an  electric  current. 

the  St.  Helen-  <li-u-tei'  there  have  been  several  other  instance-  in 
which  considerable  quantities  of  potassium  chlorate  have  exploded  in  the 
course  of  conflagrations.  On  July  27.  litns.  an  explosion  of  this  Bort  occurred 
on  the  premises  of  a  carrying  company  in  Manchester  :  2  and  on  July  21,  1910, 
another  at  the  match-works  of  Messrs.  Bryant  and  .May.  at  Seaforth,  near 

Liverj L*     In   1912  an  explosion  took  place  during  repair-  to  a  drying 

machine,  live  men  being  killed.4  Although  potassium  chlorate  i>  not  classified 
officially  a-  an  explosive,  yet  where  large  quantities  are  Btored  they  should  be 
kept  in  an  uninflammable  building,  separate  from  all  combustible  materials. 
The  intense  inflammability  of  wood  and  other  organic  matter,  when 
impregnated  with  chlorate,  should  be  borne  in  mind.  The  explosibility 
of   chloi  ui-ed   by   the   fact    that  heat  i-  liberated  when   it  decom- 

a  into  potassium  chloride  and  oxygen.     It  does  not  explode  with  great 
viol.-nce. 

Chlorate  explosives  may  be  rendered  reasonably  safe  by  adopting  the 
device  of  Sprengel  and  issuing  the  chlorate  separately  from  the  combustible 
matter.  The  potassium  chlorate  i-  made  up  into  porou-  cartridges,  and  a 
liquid  combustible  i-  used;  the  former  i-  dipped  into  the  latter  just  before 
explosives  are  not  allowed  in  Great  Britain,  as  this  dipping  opera- 
tion i-  considered  to  constitute  a  pro,,--  of  manufacture,  and  consequently 
may  only  be  carried  out  in  a  duly  licensed  factory. 

i  .7.    -        I      m.   In,/..   1902,  p.  217.  /.'..  No.    185. 

:  AJt.,   1910,  p.    »l.  *  A.R.,   1913,  p. 


CHLORATE   EXPLOSI  YKS 


379 


A  Sprengel  explosive  is  made  in  I''  ranee  under  the  name  of  "  Explosif  03  "  Promethee 
or  "  Promethee  "  ;  either  t  he  oxygen  carrier  or  t he  combustible  can  be  varied  : 


a                b 

c 

Oxygen  earner     .      92  to  87  per  cent. 
Combustible         .       8  to  13 

Potassium  chlorate.         95           90 
Manganese  dioxide  .             5              !<• 

80 

20 

!                        2 

Xitro-bcnzene 

Turpentine 

Naphtha 

50                     60 
20                     15 
30                   25 

Any  combination  of  a,  b  or  c  with  1  or  2  can  be  used.  The  explosive  is  sold 
at  the  price  of  Fr.  3  per  kg.  The  amount  of  liquid  combustible  taken  up  by 
the  solid  oxygen  carrier  may  vary  from  S  to  13  per  cent.  Tin's  irregularity 
is  a  serious  defect  and  may  cause  incomplete  detonation.1 

There  is  also  a  factory  for  Prometheus  explosive  at  Saul.  Eusebio,  near 
Genoa,  in  Italy,  where  a  severe  explosion  took  place  on  May  10,  1909,  killing 
the  manager,  head  foreman,  a  customs  officer  and  eight  workmen/and  injuring 
three  others.2 

Rack-a-rock,  which  has  been  used  very  extensively  in  America,  Siberia,  Rack-a-roi 
and  China,  consists  of  cartridges  of  chlorate  of  potash,  which  are  dipped  just 
before  use  into  a  combustible  oil.  For  this  purpose  nitro-benzene  is  used,  or 
"  dead  oil."  which  consists  chiefly  of  hydrocarbons  from  coal  tar,  or  a  mixture 
of  the  two.  The  chlorate  cartridges  are  enclosed  in  small  bags  of  cotton  : 
before  use  these  are  placed  in  a  wire  basket  suspended  from  a  spring  balance 
and  dipped  into  a  pail  containing  the  liquid,  until  a  quarter  to  a  third  of  the 
weight  of  the  chlorate  has  been  taken  up.  The  chlorate  sometimes  contains 
an  addition  of  a  few  per  cent,  of  iron  oxide.  ( 'onsiderable  quantities  of  Rack- 
a-rock  were  in  store  at  Port  Arthur  and  Dalny  at  the  commencement  of  the 
Russo-Japanese  War.  and  were  used  in  the  early  operations.8 

Promethee  is  similarly  issued  in  the  form  of  compressed  cartridges,  and 
the  French  Government  has  refused  to  make  it  in  the  form  of  grains,  as  the 
danger  of  ignition  by  friction  during  manufacture  and  use  would  be  greatly 
increased.4  The  Government  has  also  refused  to  issue  it  ready  impregnated 
with  the  "  combustible,"  as  it  would  then  possess  no  advantage  over  Cheddite.8 


1  Y.iiiiin    el    (  'liesneau,    p.    356. 

2  A.B.,   1909,  p.   35. 

*  P.  ei  S.,  vol.  xv.,   1910,  p.    130. 


:!  S.S.,   1908,  p.   19. 

■   /'.  ei  S.,  vol.  xv.,  p.    I  is. 


EXPLOSIVES 

An  explosive  of  this  sort  has,  however,  been  introduced  recently  in  Germany 
in  order  t»>  economize  nitrates  during  the  Avar.1 

If  a  charge  of  Sprengel  explosive  be  tired  with  a  primer  of  black  powder, 
it  should  be  ><>  made  op  that  admixture  is  impossible:  a  compressed  pellet 
of  black  powder  wrapped  in  impermeable  paper  may  be  used  for  instance. 
The  primer  of  black  powder  should  be  not  less  than  l»»  per  cent,  of  the  weight 
of  the  charge  with  a  minimum  of  2">  g.  (say   1  oz.). 

It  was  discovered  by  E.  A.  G.  Street,  of  the  firm  of  Berge-.  Oorbirj  el 
that  the  dangerous  sensitiveness  of  chlorate  mixtures  could  be  reduced  by 
coating  the  chlorate  with  an  oily  material,  such  as  castor-oil  thickened  by 
having  a  nitro-hydro-carbon  dissolved  in  it.2     Explosives  made  on  this  prin- 
ciple have  been  examined  from  time  to  time  by  the  French  Commission  des 
Poudres  et  Satpetres,  and  the  manufacture  of  several  lias  been  undertaken 
by  the  State.3     They  are  called  Cheddites  from  Chedde,  the  place  in  Haute 
«e,  where  the  above-named  firm  manufactures  chlorates  by  electrolytic 
methods.     It  has-been  found  necessary  to  keep  the  proportions  of  the  various 
constituents  within  certain  limits  in  order  to  produce  an  explosive  that  shall 
possess  the  right  degree  of  sensitiveness  and  shall  not  be  liable  to  exude  oil. 
It  was  also  found  that  the  velocity  of  detonation  of  Cheddite  varies  consider- 
ably with  the  density  to  which  it  is  compressed  :    with  increase  of  density 
the  velocity  of  detonation  rises  until  it  reaches  a  maximum  and  then  falls 
rapidly.     This  fall  is  due  to  the  fact  that  the  explosive  becomes  very  insensitive 
to  detonation  when   the  density   exceeds   a   certain   critical   value,   and   this 
difficulty  can  only  be  overcome  to  a  slight  extent  by  the  use  of  a  stronger 
oator.     Some  of  the  earlier  preparations  were  found  to  increase  in  density 
on  keeping  and  consequently  to  diminish  in  sensitiveness,  but  this  was  traced 
to  the  use  of  dinitro-toluene  which  had  been  insufficiently  purified.4    The 
nitro-body  Bhould  not  melt   below  60  .  else  there  i>  danger  of  exudation.5 
The  explosivi  -ily  compressed,  and  therefore  there  is  danger  of  dimin- 

ishing the  sensitiveness  too  much  if  charges  are  rammed  hard  in  the  bore- 
hole. 

Various  attempts  have  been  made  to  produce  a  satisfactory  (  heddite  in 
which  the  potassium  chlorate  i>  replaced  by  the  cheaper  sodium  salt,  which 
contains  a  larger  percentage  of  oxygen,  but  the  mixtures  first  made  were 
found  to  be  too  insensitive,  when  the  density  exceeded  quite  a  moderate 
amount,  and  very  compressible.  Moreover,  sodium  chlorate  is  very  hygro- 
scopic, and  when  ground  gives  rise  to  a  great  deal  of  dust,  which  makes  the 

5  -  .    1915,  pp.  55,  56. 

9,970  and    13,72  L  of  1891  Pat.    100,522  of   1897. 

3  P.  ,i  >■..  vol.  xi..  p.  22;    vol.  xii..  p.   L22,   L30 ;    vol.  xiii..  pp.  29,   144.  282  j    vol 
xiv..  p.   33  :    vol.  xv..  pp.  212,  247. 

*   \\  et  >..  vol.   xiv..  j).   :  5  ]'.  ,t  8.,  vol.   xiii..  p.    144. 


CHLORATE   EXPLOSIVES 


381 


worker's  clothing  and  similar  materials  very  inflammable.1  The  workers 
with  this  substance  in  the  powder  works  a1  Vonges  are  obliged  not  only  to 
change  their  clothes,  but  to  have  a  complete  bath  when  they  leave  off  work.2 
However,  it  was  found  that  a  mixture  containing  16  per  cent,  of  dinitro- 
toluene  and  no  nitro-naphthalene  could  be  fired  up  to  a  density  of  1-65  and 
Mas  more  powerful  than  the  other  types.3  The  following  Cheddites  are 
authorized  in   Prance  : 


Ol 
Tvp  41 

01 

Tvp  60  bis 

02 
TypGObisM 

05 

Potassium  chlorate      ...             80 

Sodium  chlorate 

Castor-oil  .....                 8 
Mbnonitro-naphthalene         .          .              12 
Dmitro-toluenc   .... 
Paraffin      ..... 

Price,  Fr.  per  kg.       .          .          .               21<» 

80 

5 
13 

2 

210 

79 

5 

I 

15 

2-30 

79 

5 

1(3 

The  Cheddites  most  made  in  France  are  n-2  (otherwise  Cheddite  No.  4),  accord- 
ing to  formula  60  bis  M,  and  0-5  (otherwise  Cheddite  Xo.  1). 

In  making  Cheddite  the  nitro-compounds  are  first  dissolved  in  the  castor-  Mauufactu 
i  il  at  80°  C.  and  the  finely  powdered  dry  warm  chlorate  is  then  added  gradu- 
ally, whilst  the  mass  is  stirred  with  a  wooden  rod.  The  incorporation  of  a 
charge  of  25  kg.  lasts  about  ten  minutes.  The  material  is  then  carried  to 
another  building,  where  it  is  further  mixed  on  a  wooden  board  in  a  half-cold 
condition  for  another  ten  minutes,  so  as  to  get  it  in  a  suitable  granular  con- 
dition. Each  particle  of  chlorate  should  be  entirely  coated  with  the  oily 
mixture.  The  material  is  next  sifted,  and  what  is  too  fine  is  added  to  a  later 
charge.  That  which  is  of  the  correct  size  is  made  into  cartridges  by  ramming 
it  into  wooden  moulds,  from  which  it  is  transferred  to  paper  cases.  If  the 
explosive  contain  sodium  chlorate,  the  cases  should  then  lie  dipped  into 
molten  paraffin  to  prevent  the  absorption  of  water.  If  the  percentage  of 
moisture  rise  above   1   per  cent.,  the  explosibility  is  impaired. 

Cheddite  is  a  sofl  yellowish  material  of  tine  grain,  but  is  sometimes  arti- 
ficially coloured.  In  consequence  of  its  plasticity  it  can  easily  be  compressed. 
ft  is  generally  put  up  into  cart  ridges  22  cm.  long  and  2*6  cm.  diameter.     I  Ihed- 


1  P.  (I  S.,  vol.  \i\..  p.  26;    vol.  w.,  p.   135. 
-  Vennin  <'t  Chesneau,  |>.   12.'!. 

:!  /'.  et  S.,  vol.  xvi..  p.  f.ii. 


EXPLOSIVES 

dite  41  i-  a  slow  mild  explosive,  which  splits  rooks  rather  than  shatters  them. 

<  heddite  60  is  more  violent,  and  the  Sodium  Clorato  Cheddite,  (>.">.  >till  more 

The  velocity  of  detonation  <»f  Cheddite  <>n  was  measured  by  Lheure  ] 
and  found  to  be  ol7.'>  metres  per  sec.,  about  half  of  that  of  picric  acid.  Masting 
gelatine,  and  other  very  high  explosives,  and  that  of  02  2750  metres  per 

Many  other  mixtures  on  the  same  principle  as  cheddite  have  been  tried 
in  France  and  elsewhere,  such  as  <>4.  a  mixture  of  90  parts  potassium  chlorate 
and  in  paraffin  wax.'5  Sebomite  containing  tallow  and  dinitro-benzene  or 
uitro-toluene 4  06  or  minelite  containing  heavy  petroleum,  mineral  jelly  and 
paraffin  was 

insists  essentially  of  potassium  chlorate,  the  particles  of  which 
aveloped  in  oxidized  resin,  which  is  made  as  follows  :  9  parts  of  ground 
colophony  arc  mixed  with  1  part  of  starch,  and  to  this  mixture  nitric  acid 
of  1-41  specific  gravity  (67-5  per  cent.  HX03)  is  added  at  the  ordinary  tempera- 
ture, without  the  addition  of  any  sulphuric  acid.  An  oxidized  yellow  amor- 
phous ma—  is  thus  formed,  winch  floats  on  the  top  of  the  acid.  This  is  broken 
up.  washed  with  water,  dried  at  a  moderate  temperature,  and  ground  up. 
It  is  not  explosive  without  the  addition  of  chlorate,  and  only  burns  with 
difficulty.  It  is  mixed  with  the  ground  chlorate  and  other  constituents  in 
a  drum  with  lignum  vitaa  halls.  The  mixture  is  spread  on  a  zinc  sheet  in 
quantities  of  1  to  5  kg.  and  sprinkled  with  methyl-alcohol,  whilst  it  is  raked 
a  Ik. iit.  so  that  a  paste  or  dough  may  not  be  formed.  It  is  kepi  in  gentle  motion 
with  a  wooden  tool  until  it  is  dry. 

ral  samples  of  Steelite   wen  examined  by  the  French  Commission 

Explosives,     but    it    was    decided    not    to    undertake    its 

manufacture     on     the     ground     that     it     possessed    no     advantages    over 

<  heddite.  than    which    it   was    more    sensitive    and    less    dense.4      Colliery 

ite  containing  a  small  percentage    of  castor-oil   passed    the  Woolwich 
for    Bafety  explosives  and  was  formerly    on    the    English    "permitted 
list." 

In    Germany    this   explosive  is  called    "  Silesia  "  :    unoxidized    resin    is 

apparently    used  in    it    sometimes,    and  to    make  it    pass  the  Continental 

for  Bafety  explosives  a    considerable    proportion    of    sodium    chloride 

is  added.     The  folh. win-    are  some  of    the   compositions    that    have    been 

made  : 

1  P.        ?.,  voL  xii..  p.   117.  -  \ .  mnii  it  Chesneau,  p.  359. 

3  v  ?.,     oL  xv.  pp.  212,  J4T,  also  1st  ed.  of  this  work,  p.  208,  and  Vermin  et 

4  V.    •      ^  .   vo\.   xiii..   p.   280,  and  vol.   xv..   p.    1 

5  /'  .  \\ ..  p.  212;    Venom  el  Chesneau,  p. 
*    I                  vo\.   xv..  p.    181, 


CHLORATE    KXPL<  >S[YES 


383 


Colliery  Steelite 

No.  3 

N'n.    5 

Silesia  IV  22 

Silesia  4 

Potassium  Chlorate 

72*5-75'5 

7.-. 

79-2 

70 

so 

Oxidized  resin 

23-5-26-5 

25 

15-8 

8 

20 

Castor-oil    . 

0-5-  1 

— 

— 

— 

— 

Aluminium 

— 

— 

5 

— 

— 

Sodium  chloride. 

— 

— 

— 

22 

— 

Moisture 

ti    -  1 

The  Silesia  explosive  has  a  large  excess  of  chlorate,  and  the  gases  produced 
contain  14-2  per  cent  of  free  oxygen.1 

In  Austria  a  chlorate  explosive  called  Chloratit  has  been  sanctioned  for 
use  in  coal  mines  during  the  war.2  It  gives  rise  to  bad  fumes  and  is  hygro- 
scopic. 

Chlorates  should  never  be  mixed  with  ammonium  salts,  as  ammonium 
chlorate  would  be  formed,  and  this  is  liable  to  explode  spontaneously.  Mix- 
tures with  picric  acid  or  trinitro-cresol  also  should  not  be  made,  as  they  are 
verv  sensitive. 


POTASSIUM  PERCHLORATE  EXPLOSIVES 

The  perchlorates  possess  the  advantage  over  the  chlorates,  that  they 
are  more  stable  and  less  sensitive,  although  they  contain  a  larger  pro- 
portion of  oxygen.  Consequently  explosives  containing  perchlorates  do 
not  require  to  have  each  particle  encased  in  fatty  matter,  as  is  the 
case  with  chlorate  explosives.  Since  the  introduction  of  electrolytic 
methods  of  manufacturing  perchlorates.  these  explosives  have  been  used 
extensively.  A  certain  amount  is  obtained  as  a  by-product  in  working  up 
Chili  nitrate  :  rn>  tons  of  potassium  perchlorate  were  exported  from  Chile  in 
1914. 

Explosives  containing  potassium  perchlorate  and  ammonium  nitrate  Permonite. 
together  with  trinitro  toluene,  starchy  matter  and  wood-meal,  are  made  by 
the  Sprengstoff-A.-G.  Carbonif  under  the  name  of  "Permonite."  One  of 
these  compositions  was  formerly  on  the  English  "■  permitted  list."  and  another 
is  on  the  Belgian  list  of  Explosifs  S.G.P.  Gesteins-Permonil  i-  used  in  potash 
and  ore  mines.  The  following  are  the  compositions,  together  with  other 
particulars  ;i-  stated   by  the  makers: 


1  See  Bscales,  Chlorataprengstoffe,  191<»,  p.   14.'?, 
v.   L915,  p.  294, 


EXPLOSIVES 


Permonit  I 

•nite 

Permonite 

or  Gesteins- 
Permonit 

-     .P. 

(Permitted 

Pota-ssium  perchloral 

e 

24  .". 

31     -34 

Nitre-glycerine. 

— 

6 

3-4 

Collodion  cotton 

— 

— 

1 

Ammonium  nitrate 

4" 

- 

-43 

B     Limn  nitrate 

. 

— 

— 

Trinitro-toluene 

15 

7 

11    -13 

Sodium  chloride 

— 

25 

— 

or 

4 

4 

— 

34    rch 

— 

— 

5-9 

>d-meal 

3 

3 

1-5-  3-5 

Jelly 

1 

1 

— 

Moist  on 

— - 

— 

<» 

Influence  test    . 

am. 

100  mm. 

-     mm. 

Trauzl  test 

.      e.c. 

c.c. 

365  c.c. 

Velocity  of  detonation 

347"  m   sec. 

2o2'«  m 

— 

Sensitiveness,     2  kg.  weight 

7"  cm. 

-     cm. 

2"  cm. 

10  kg. 

5 

10 

The  '•  charge  limite 
dvnamite  No.    1. 


of  Permoni:-    >.'  LP.  is  900  g.,  equivalent  to  about   570  g.  of 


The  '*  jelly  "  is  a  mixture  of  1  part  glycerine  and  35  parte  gelatine  :  the 
influence  test  consists  in  ascertaining  the  distance  over  which  detonation  is 
conveyed  from  one  30  em.  cartridge  to  another  lying  on  the  ground.     Another 

nanexp]  milar  to  Permonit,  bnt  not  so  powerful,  is  Wetter-PeraaKt. 

Another  very  similar  explosive  made  in  Germany  is  Alkalsit.  Polarite. 
a  non-freezing  explosive  of  high  power,  is  used  in  England  as  a  substitute 
for  Gelignite. 

ral    ex;  ontaining   potassium    perchlorate    have    passed    the 

Rotherham  te>t.  and  are  on  the  English  Permitted  List.  They  differ  bom  the 
Permonites  in  that  they  contain  a  larger  proportion  of  nitro-glycerine  and 
wood-meal,  and  the  ammonium  nitrate  has  been  replaced  by  oxalate,  so  that 
they  are  not  hygroscopic.     The  result  is  that  instead  "f  an  excess  of  available 

_ii  they  contain  a  Blight  deficit. 

I-    _     -ral  method  of  manufaeturi:  _  explosive  -    b     -  Follows  :  The 

oxalate,  perchlorate  and  wood-meal  are  all  sifted  and  placed  in  a  pan  and 
mix-  _  roughly  by  hand.     The  nitroglycerine,  which  has  been  par- 

tially gelatinized  with  the  collodion  cotton  the  day  before,  is  poured  on  top, 
the  last  portion  of  jelly  being  wiped  <>ut  with  some  wood-meal  which  has  been 
kept  back  f«»r  tin-  purpose.  The  composition  is  then  incorporated  in  a  gelatine 
incorporator  for  about  an  hour  at  a  temperature  not  higher  than  30 


(ULOKATU    EXPLOSIVES 


385 


Dynobel 

Neonal 

Neonal 

Ajax 

Swale 

No.  1 

Powder 

Powder 

Potassium  perchlorate 

27 

37 

14 

37-2 

37-5 

Nitro-glycerine 

32-5 

21 

40 

22-5 

19 

Collodion  cotton 

0-7 

0-8 

2-8 

0-8 

I 

Di-  and  tri-nitro-toluene   . 

— 

0-2 

— 

:;•:, 

4 

Ammonium  oxalate. 

29-5 

25 

39 

25 

28 

Wood-meal      .... 

10-3 

L6 

5 

11 

10-5 

Maximum  charge 

22  oz. 

Hi  oz. 

30  oz. 

12  oz. 

20  oz. 

Power  (swing  of  bal.  pend.) 

2-61" 

2-56" 

2-51" 

2-09" 

2-50* 

The  addition  of  nitro-toluenes  renders  the  explosives  less  liable  to  freeze. 

A  different  type  of  perchlorate  explosive  is  represented  by  M.B.  Powder  m.b.  powder 
(Modified  Black),  which  consists  of  black  powder  in  which  part  of  the  salt- 
petre has  been  replaced  by  potassium  perchlorate.  It  is  made  in  much  the 
same  way  as  Safety  Blasting  Powder  was,  that  is  to  say  the  ingredients,  after 
a  preliminary  mixing,  are  incorporated  together  in  a  steam-jacketed  pan. 
On  November  25,  1911,  a  severe  fire  occurred  in  the  house  where  this  operation 
was  being  carried  out,  whereby  three  men  were  killed  and  one  was  injured, 
it  Mas  ascribed  to  friction  on  dry  caked  material  in  the  steam-heated  incor- 
porator.    Another  similar  explosive  is  Roslin  Giant  Powder. 


AMMONIUM  PERCHLORATE  EXPLOSIVES 

As  a  constituent  of  an  explosive,  ammonium  perchlorate  possesses  the 
advantage  that  it  contains  a  high  proportion  of  available  oxygen  and  only 
produces  gaseous  products,  but  unfortunately  these  include  the  poisonous 
gas  hydrogen  chloride.  The  formation  of  this  can  be  jn-e  vented  by  adding 
an  equivalent  quantity  of  some  substance  such  as  sodium  nitrate,  which  will 
yield  a  base  to  combine  with  the  chlorine.  In  1006  the  French  "  ( lommission 
des  Substances  Explosives  '"  investigated  two  Cheddites  containing  ammon- 
ium perchlorate,  and  although  it  was  decided  not  to  undertake  their  manufac- 
ture some  of  the  experiments  are  instructive.3  The  explosives  had  the 
compositions  : 

I.  II. 

Ammonium  perchlorate       ....  82  50 

Dinitro-toluene  .           .           .           .           .           .  1  .'5  I  •"> 

Sodium  nitrate  .           .           .           .           .           .  —  30 

Castor-oil  .......  5  •"• 

1  P.  ei  8.,  vol.   \iv..  pp.    L92,  206. 

VOL.  i.  25 


g 


EXPLOSIVES 


I   burns  with  dangerous  rapidity  when  ignited,  but  IT  is  quite  safe  in 
\h\>  respect.     Fabrics  impregnated  with  ammonium  perchlorate  are  more 
inflammable  than  when  potassium  chlorate  is  used,  but 
with  sodium  chlorate.     Ammonium  perchlorate  is  a  mild  explosive  by  it -elf. 


■ 

I 

190 

180 

Ul 

ltd 

ISO 

1*0 

130 

^ 

v?c 

' 

V 
*000  10° 

j 

i  ^- 

$* 

r^™ 

o&o 

0.70 

060 

,  ■.'■ 

\ \  i 

?000  Cx 

o*c 

030 

0?0 

010 

j •.  ,  ■ 

v.-.* 

o-   o 

1 

0      0.1     02     03    0*     Oi     06    07     0.8     OS    100    110    120    130    1*0    1iC    .1 

tion  of  Ammonium  Perchloi  Idite  at   Dim: 


but  i>  only  exploded  with  difficulty  and  incompletely  :   at  ordinary  tempera- 
tures it  is  stable,  but  at  150    decomposition  Bets  in  after  a  time  and  proceeds 
equation:     XH,(  1<  >,  =  <  1  —  <  > .  —  X  —  2B  _<  I 
il.     The  reaction  is  apparently  auto-catalytic.1     It  i>  very  important 
that  ammonium  perchlorate  be  kept   quite  separate  bom  the  chlorati  - 
sodium  and  potassium,  as  dangerous  double  decompositions  are  liable  to 

braid  and  Lore  .  April,  1909;    SJS.,  134. 


CHLORATE    EXPLOSIVES  387 

occur.  Ammonium  perchlorate  lias  about  the  same  degree  of  sensitiveness 
to  impact  as  picric  acid  :  a  5  kg.  weight  falling  50  cm.  causes  explosion 
sometimes.     As  in  the  case  of  other  Cheddites  the  velocity  of  detonation 

rises  with  increase  of  density  to  a  maximum,  after  u  bich  if  falls  in  consequence 
of  the  diminution  of  the  sensitiveness  to  detonation.  This  is  clearly  shown 
by  the  curves  in  Pig.  70,  which  gives  the  velocities  of  detonation  and  the 
weights  of  fulminate  required  to  detonate  explosive  I.  when  loaded  into 
cartridges  at  different  densities. 

A   number   of  explosives   of   this   type   were   made    iii    Belgium    under   theYonckite. 
name  of  Yonckites.     One  of  these  No.  L0  bis  is  on  the  Belgian  list  of  Explosives 
S.G.P.,  No.  13  is  of  a  more  brisant  type  : 


in  bis 

L3 

Ammonium -perchlorate 

.      25 

20 

Ammonium  nitrate     . 

.      30 

27 

Sodium  nitrate 

.      15 

27 

Barium  nitrate  .... 

.     — 

6 

Trinitro -toluene . 

.      10 

20 

Sodium  chloride 

.     20 

— 

The  "  charge  limite  "  of  10  bis  is  900  g.,  equivalent  to  540  g.  dynamite  No.  1. 
To  make  these  explosives  the  perchlorate  and  nitrates  of  sodium  and  barium 
are  milled  together,  as  also  are  the  ammonium  nitrate  and  trinitro-toluene. 
The  two  mixtures  are  then  incorporated  together  in  a  Pfleiderer  machine. 
These  explosives  were  examined  by  the  French  Commission  des  substances 
explosives,  but  it  was  decided  that  they  possessed  no  marked  advantage  over 
the  Cheddites.1 

An  explosive  which  is  now    being  used  extensively  is  Blastine,  in  which  Biastine. 
ammonium  perchlorate  and  sodium  nitrate  are  mixed  with  the  combustible 
matters,  dinitro-toluene  and  paraffin  wax. 

1  P.  et  S.,  vol.  xvii.,  p.    170  ;    Vermin  ct  Chcsncau,  p.   3G2. 


Favier  explo- 
sives. 


Manufacture. 


Explosifs  N  or 
Grisounites. 


CHAPTER   XXVII 

AMMONIUM  NITRATE  EXPLOSIVES 

Favier  explosives  :    Grisounites  :    Ammonals  :    SabulnV  itine 

Attention  was  first  drawn  prominently  to  the  use  of  ammonium  intra* 
a  constituenl  of  explosives  in  consequence  of  the  numerous  explosions  of  coal 
damp  and  dust  in  mines.  The  low  temperature  of  explosion  of  mixtures 
containing  large  proportions  of  ammonium  nitrate  indicated  its  use  for  this 
purpose.  Ammonium  nitrate  explosives  are  used  now  very  extensively,  not 
only  in  coal  mines,  but  also  for  general  blasting  work,  and  the  introduction 
of  synthetic  methods  for  the  manufacture  of  ammonia  and  nitric  acid  is  likely 
to  lead  to  further  developments  in  this  direction.  In  1884  and  lss~>  Favier 
took  out  patents  for  mixtures  of  ammonium  nitrate  with  mononitro-naphtha- 
lene.  paraffin  and  resin.1  The  manufacture  was  Boon  afterwards  undertaken 
by  the  French  Government  and  is  still  continued  under  the  name  of  Explosifs 
N,  or  Explosifs  Favier.  or  Poudres  de  surete. 

The  ammonium  nitrate  is  first  dried  and  then  ground  in  a  mill,  the  pan 
of  which  is  heated  by  -team  or  hot  water.  The  nitro-naphthalene  is  then 
added,  and  the  incorporation  is  carried  on  for  an  hour  or  two  in  a  warm  dry 
room.  The  mass  is  then  allowed  to  cool  and  is  ground  to  a  powder,  after  which 
it  is  loaded  into  cartridges.1  In  some  cases  the  cartridges  are  formed  under 
considerable  pressure,  but  in  that  case  it  is  necessary  to  remove  the  core  and 
introduce  a  primer  of  the  powdered  explosive,  because  if  the  density  he  to,. 
high,  the  explosive  i-  very  difficult  to  detonate.  In  other  cases  the  eartr 
are  formed  under  a  moderate  pressure  only,  such  as  that  produced  by  an 
Archimedean  screw  working  against  a  slighl  resistance.  The  cartridges  are 
contained  in  wrappers  of  metal-foil  or  paper  rendered  waterproof  by  dipping 
in  a  hath  of  paraffin-wax.  According  to  the  German  regulations  for  the 
manufacture  of  ammonium  nitrate  explosives  the  temperature  of  the  Max 
hath  must  not  exceed  100  C.  Waterproofing  i>  absolutely  necessary  because 
ammonium  nitrate  is  extremely  hygroscopic. 

The  composition  of  tin-  Favier  explosives  made  in  France  has  been  varied 

1  Ger.  Pat.  31,411  of  May  27,  Ism:    Eng.  Pat.  2139  of  February   L6,  1981 
-  See  aiao  V.  <t  ST.,  vol.  lv.,  p.  159. 


AMMONIUM  NITRATE  EXPLOSIVES 


389 


from   time   to   time.      The   following   were   the  authorized  compositions  of 
Explosifs  N  according  to  Vennin  et  Chesneau,  pp.  345,  562. 


Grisou- 
naphtalite- 

couche 

( irisou- 
naphtalite- 

roche 

tetrj  lite 

couche 

For 

mines 

Eree  from 

fire-damp, 

etc. 

N,c 

X,a 

N*. 

X,l. 

Ammonium  nitrate 

Potassium  nitrate 
Dinitro-naphthalene    . 
Trinitro-naphthalene  . 
Tetryl        .... 

95 
5 

90            91-6 
5 

8-5 
5             — 

86-5            88 
5                  5 

8-5 

—                7 

87-4 
12-6 

The  Grisoiinites-couches  are  used  in  the  coal  seams  as  the}7  have  theoretical  tem- 
peratures of  explosion  of  1500°  or  less,  but  N  va>  has  been  replaced  to  a  considerable 
extent  by  X  , ;  these  are  both  coloured  with  methylene  green  B.  The  Grisounites- 
roches  have  theoretical  temperatures  of  explosion  of  1900°  or  less,  and  are  for 
use  in  the  rocks  in  coal  mines  ;  Nxb  is  dyed  rose  colour,  and  NiC  pale  yellow. 
The  sensitiveness  of  these  explosives  diminishes  rapidly  with  increasing 
density  ;  thus  for  the  detonation  of  an  explosive  composed  of  90  per  cent. 
ammonium  nitrate  and  10  per  cent,  mononitro-naphthalene  detonators 
containing  the  following  weights  of  fulminate  were  required  :  l 

Density  of  explosive 
0-9 
10 


11 
1-2 

above  1-2 


The  following  are  some  of  the  princi 


Weight  of  fulminate 
0-4  g. 
1 
2 
5 
misfires 


pal  explosives  that  passed  the  Woolwich 


tesl   and  so  obtained  a  place  on  the  Permitted  List 


An  a  non- 

Westfalite 

Bellite 

Roburite 

ite 

1 

2 

'      l 

3 

3 

Ammonium   nitrate 

Potassium  nitrate 

Dinitro-naphthalene 

Dinitro-benzene 

Chloro-naphthalene 

Resin          .... 

88              95 
12 

5 

91            83-5 
4 

16-5 
5       1       - 

93-6            88 

6-5             11 
1 

Gody,  p.  694. 


EXPLOSIVES 


In  order  to  pass  fche  Rotherham  test,  in  which  the  explosive  is  fired  without 
stemming  into  the  gas  mixture,  the  compositions  have  had  to  be  modified 
some  what  : 


Ami 

[lite 

Fa  i 

sham 
•ler 

No.  1  j 

•2 

N      4 

N       - 

N      2         \       4 

Ammonium  nitr. 

im  nitrate 
Trinitro-tolm 
Dinitro-bt-n/' 
Ammonium  chloride 
S     limn  chloride 
lib 

Limit  charge 

Power  (swing  of  bal. 

) 

75 

5 

24  oz. 
2  42" 

til 

12 
21 

I     OB. 

2-42* 

14 

- 

1  S  oz. 

24 
10 

24   oz. 
-  SI* 

i:. 

24   oz. 
2  21* 

61 
16 

! 

In  Belgium  the  following  are  on  the  li>t  of  Ex]>lo-if>  S.G.P.  ; 


4 

3  bis 

;Jre 
■ 
3               mil 
1  bis 

- 

Frac- 
B 

anti- 
grisout- 

Ammonium  nitrate 
Potassium  nitrate 
Sodium  niti 
Potassium  permanganate 

d  chromate 
Trinitro-toku 
Trinitro-naphthal 
1  tinitro-naphthal* 
Flour 

Ammonium  oxalate  . 
Alum 

Ammonium  chloride . 
urn  carbonati 

Charge  limite  g    . 
valent,   Dyn.   No. 

18 

r  nt 

.  = 

r 
549 

60 

11 

0 

5 
4 
5 

760 

4:.  2 

74 

4 

310 

1 
1 
3 

18 

72 

AMMOMI  M    NITRATE   EXPLOSIVES  391 

The  following  are  the  results  given  by  some  German  safety  explosives 
tested  at  the  Gelsenkirehen  testing  station  :  x 


Roburit 

Cllirl, 

auf 

Neu- 

Westfalii 

ll2 

III 

AI 

AIII 

Ammonium  nitrate  . 
Potassium  nitrate     . 

71-5 
5 

55 
9-5 

70-3 

70-4 
10 

82-7 

Potassium  permanganate . 

0-5 

0-5 

1 

1 

Dinitro -benzene 

— 

Dinitro-toluene 

— 

— - 

10-9 

Trinitro-toluene 

12 

12 

6-4 

11-5 

Wood-meal 

— 

■    ■ 

Flour       .          •          •          • 

6 

6 

2 

7-2 

Fennel  (?) 

Ammonium  chloride 

— 

5 

Sodium  chloride 

5 

7 

16-8 

Magnesite 

■     ■ 

5 

5 

4-8 

Copper  oxalate 

Limit  charge,  g. 
Trauzl  test,  c.c.    . 

350 
325 

650 

257 

540           400 
309           312 

450 
341 

Other  German  Favier  ei 

^plosives  are  : 

Dc 

rfit 

Wetter- 

Dahmeni 

-   Aldorfit 

Fulmeni 

Fulmenil 

I 

I 

II 

Ammonium  nitrate 

91-3 

65 

61 

81 

86-5 

76-5 

Potassium  nitrate 

— 

5 

5 

Potassium  bichromate 

2-2 

~~ 

4 

4 

Gun-cotton 

■ — • 

Trinitro-toluene 
Paraffin  oil 

— 

6 

15 

17 

5-5 
2-5 

2-5 

Rye  flour  . 

— 

4 

4 

2 

— 

Naphthalene 

6-5 

— 

1-5 

1-5 

Charcoal     . 

— 

■ — 

10 

Sodium  chloride 

— 

20 

15 

Limit   charge,  g. 

. — . 

532 

300 

— 

— 

Trauzl  test ,  c.c. 

172 

219 

! 

1  S.S.,  1907,  p.   13. 


- 


EXPLOSIVES 


Monachit  I 

Monachit  lid 

.      81 

04 

5 

— 

.      13 

12 

1 

1 

— 

1 
19 

of  these  Aldorfit  and  Fulmenit  are  not  intended  for  use  in  dangerous  coal- 
mines. Dorfit  and  Wetter-Pulmenit  differ  from  them  in  containing  consider- 
able pero  .  -  sodium  chloride  which  reduces  the  temperature  of  explosion, 
ichit  contains  crude  trinitro-xylene  made  by  nitrating  a  fraction  of 
benzol.  The  nitro-product  may  be  .solid  or  liquid,  but  must  not  contain  more 
than  60  per  cent,  of  trinitro-bodio  : 

Ammonium  nitrai 

Potassium  nitrate 

Sodium  nitrate 

Trinitro-xykne  .... 

Collodion  cotton 

Flour  ..... 

(  hareoal    ..... 

Alkali  cliloride  .... 

Monachit  lid  has  a  limit  charge  of  more  than  500  graninc 

Under  the  name  of  Raschit,  Raschig  has  recently  introduced  a  number  of 
explosives  containing  ammonium  nitrate  and  highly  soluble  organic  Mil»tances 
such   as  ammonium  mononitro-cresol-sulphonate,   sodium   cresol-sulphonate, 

or  the  residue  obtained  in  the  manufacture  of  -wood  cellulose.     The  incor- 
poration i-  carried  out  by  dissolving  the  constituents  in  water  and  evaporating 
solution  rapidly  on  a  rotating  steam-heated  drum. 
An   ammonium  nitrate  explosive  manufactured  in   Denmark   under   the 
name  of  Aerolit  has  the  composition  : 

Anuuonium  nitrate  .  .  .  .78-125 

Potassium  nitrate 
Sulphur         .... 
Fat   (beef  suet ) 
Sago  flour    .... 
Manganese  dioxide 
-in  . 

LOO 

The  sulphur,  fat.  resin  and  manganese  dioxide  are  melted  together,  and  the 

potassium  nitrate  and  Hour  stirred  in,  and  the  mass  is  allowed  to  cool  and  is 
powdered.  Then  the  ammonium  nitrate  is  added  and  the  mixture  is  again 
melted,  cooled  and  powdered.2 

The  Austrian  Government  manufacture  as  safety  explosiv< 

1  >\  iiammon  WVtter-Dvnammon 
87-88 


7." 

8-75 

2-5 

1  -25 

1  2 

0 

Ammonium  nitrate. 
--iuin  nitrate 

Charcoal 

aty  . 


12   13 


■2 
4 

0-85 


S.S.,  1913,  p.   13ft. 


the  velocity  of  detonation  <-f  Monachit   I.  aw    H. 

-  Danish  Pat.  l'.t.sr.s.  8J5.,  L905,  p.  _ 


AMMONIUM  NITRATE   EXPLOSIVES 


393 


The  idea  of  utilizing  the  great  amount  of  heat  energy  that  is  liberated  in  Ammonal, 
the  oxidation  of  aluminium  has  formed  the  subject  of  patents  taken  out  by 
G.  Roth,  of  Vienna,1  and  mixtures  of  ammonium  nitrate,  aluminium,  and 
other  substances  have  been  brought  on  the  market  mostly  under  the  name 
of  Ammonal.  In  spite  of  the  high  temperature  produced  by  the  oxidation 
of  aluminium  three  of  these  compositions  Mere  able  to  pass  the  Woolwich  test. 


Ammonal  B 

Ripping 
Ammonal 

St.  Helens 

powder 

Ammonium  nitrate    . 
Aluminium         .... 
Charcoal  ..... 
Trinitro  -toluene 
Potassium  bichromate 
Moisture  .          .          .          . 

93-95-5 

2-5-3-5 
2-3 

0-1 

84-87 
7-9 
2-3 

3-4 
0-1 

92-95 
2-3 

3-5 

0-1 

72 

47 

25 

22 

3 

1 

— 

30 

For  safety  in  coal-mines  it  is  necessary  to  keep  down  the  percentage  of 
aluminium.  In  Ripping  Ammonal  the  safety  is  increased  by  the  addition 
of  potassium  bichromate,  and  consequently  the  proportion  of  aluminium  can 
be  increased.2  For  ordinary  blasting  purposes  compositions  such  as  the 
following  are  used  : 

Ammonium  nitrate 
Alurninium      ..... 
Charcoal  ..... 

Trinitro -toluene        .... 

Ammonal  is  an  explosive  of  considerable  power.3  The  velocity  of  detonation 
of  an  Ammonal  was  found  by  Bichel  to  be  3450  metres  per  second.  The 
aluminium  powder  used  for  making  ammonal  should  not  be  too  fine.4  The 
density  of  ammonal  is  usually  about  1  or  slightly  more. 

Two  explosives  of  this  class  are  manufactured  in  Germany  under  the  name 
of  Gesteins-Westfalit  B  and  C  :  B  contains  dinitro-benzene  and  ( !  dinitro- 
toluene.  Roth's  Ammonal  patent  has  been  contested  in  Germany,  but  on 
June  24,  1911,  it  was  confirmed  by  the  Courts. 

In  Switzerland  an  explosive  similar  to  Gesteins-Westfalit  C  is  made  under 
the  name  of  Telsit  A. 


1  Ger.  Pat.   172,327  of  June  28,  1900;    Eng.  Pat.   10,277  of  September   13,   1900. 
-  Eng.  Pat.  16,514  of  1905,  W.  Macnab  and  Ammonal  Explosives  Ltd. 
;;  See  Bichel,  Aug.,  1905,  p.  1889;   also  S.S.,  1906,  p.  2<i  ;   Rudolph,  Kriegstechnishe 
Zeitschrift,  1907,  p.  233;    Bravetta,  S.S.,  1906,  p.   199,  and   L907,  p.  13. 
4  P.  Hess,  Aug.,  1904,  p.  551. 


394 


EXPLOSIVES 


The  Ammonals  manufactured  a1  the  Felixdorf  Powder  Works  in  Austria 
(G.  Roth  A.G.)  have  the  following  composition: 


a                       h 

c 

d 

Ammonium  nitrate        ....            80-75                 90 
Aluminium              .....             15                          4 
Charcoal      ......            4-25                0 

88 
8 
4 

80 

18 

-> 

Ammonal  is  not  allowed  to  be  used  in  fiery  mines,  but  only  where  dynamite 
would  be  permitted.1 

The  effect  of  adding  aluminium  to  an  ammonium  nitrate  explosive  was 
investigated  by  Biehel,2  who  obtained  the  following  results: 

Explosive  : 

Ammonium  nitrate 
Aluminium. 

Charcoal  (red) 

Density        .... 

Velocity  of  detonation,  m/sec.    . 
Seal  of  explosion  in  calorimeter 

Products  of  explosion  : 
( larbon  dioxide    . 
Carbon  monoxide 
Water 
Oxygen 
Nitrogen 
Methane 
Hydrogen    . 
Aluminium  oxide 

Volume  of  permanent  gas,  N.T.P. 

,,  water  vapour    . 

Total  volume     .... 

Explosion  pressure  (calculated)   • 
Trauzl  test         .... 

Biehel  considers  that  the  results  of  the  Trauzl  test  are  misleading,  because 
the  greal  heal  of  the  explosion  in  the  case  of  the  aluminium  explosive  melts 
the  surface  of  the  lead  and  so  makes  the  apparent  expansion  of  the  hole  greater. 
The  Felixdorf  Powder  Works  contend,  however,  thai  ammonal  is  a  very 
powerful  explosive  :  when  exploded  on  top  of  a  small  lead  cylinder,  ii  com- 
presses i!  considerably  more  than  a  gelignite  containing  <'••"»  per  cent,  nitro- 
1  S.S.,  1910,  ]».  54.  a  Ang.,   1905,  p.   1889. 


)\  naminon 

Ammonal 

95-5 

726 

— 

23-5 

4-5 

4-5 

•805 

•900 

3380 

3450 

727-0 

L600-5  Cal. 

1314 

7-00 

— 

4-57 

49-00 

1414 

2*60 

— 

34-66 

28-47 

— 

0-26 

— 

119 

— 

44-38 

300 

418  litres 

617 

L76 

976 

594 

0338 

9  L25  kg  sq.cm 

250 

329  c.c. 

AMMONIUM  NITRATE   EXPLOSIVES 


305 


glycerine,  and  it  breaks  up  a  shell  more  than  an  equal  weight  of  cast  picric  acid.1 
The  French  Commission  des  Substances  Explosives  found  that  the  addition  of 
aluminium  does  not  greatly  increase  the  useful  effect  on  rock,  but  it  makes 
the  explosive  easier  to  detonate  even  if  only  3  per  cent,  be  present.2 

A  somewhat  similar  explosive  is  Sabulite  which  contains  calcium  silicicle  Sabuiite. 
and  trotyl  with  or  without  the  addition  of  potassium  nitrate  and  ammonium 
chloride,  the  latter  constituents  being  added  to  make  it  safe  in  coal  mines. 
On  the  Belgian  list  of  Explosifs  S.G.P.  is  : 

Sabulite  antigrisouteuse  A 
Ammonium  nitrate         ....        54 
Potassium  nitrate  .  •  •  .22 

Calcium  silicide      .....  5 

Trotyl 6 

Ammonium  chloride       .  .  •  .13 

Maximum  charge  ....      900  g. 

Equivalent  to 596  g.  dynamite  No.  1 . 

The  only  explosives  allowed  in  the  more  dangerous  French  coal-mines,  Grisoutine 
in  addition  to  the  Grisounites,  are  the  Grisoutines  (otherwise  Grisou-dynamites), 
which  consist  of  ammonium  nitrate  mixed  with  blasting  gelatine.  As  the 
State  monopoly  does  not  extend  to  explosives  containing  nitro-glycerine, 
these  are  made  by  private  firms,  but  the  compositions  are  regulated  by  the 
State.  In  1911  the  "  Commission  des  Substances  Explosives  "  resolved  that 
the  compositions  should  be  unified  as  follows  : 


Couche                                       Roche 
Couche                 au                  Roche                  au 

Salpetre                                    Salpetre 

Nitro-glycerine   .... 
Collodion  cotton 
Ammonium  nitrate 
1  Potassium  nitrate 

120                  12-0                   29 
0-5                   0-5                     1 

87-5                 82-5                  70 
—                    50                  — 

29 
1 

65 
5 

The  calculated  temperatures  of  explosion  of  the  Grisoutines  Couche  are  below 
1500°,  those  of  the  Grisoutines  Roche  below  1900°.  The  addition  of  5  per 
cent,  saltpetre  instead  of  the  same  quantity  of  ammonium  nitrate  has  been 
found  to  increase  the  safety,  probably  because  the  potassium  compounds 
formed  are  dissociated  and  vaporized  at  the  temperature  of  explosion,  and 
afterwards  give  up  again  the  energy  they  have  absorbed,  so  that  the  effect 
is  not  very  much  less.  It  is  estimated  that  the  explosives  with  5  per  cent. 
potassium  nitrate  are  about   .">  per  cent,  weaker  than  the  others.8 

A  number  of  explosives  similar  to  these  passed  the  Woolwich  test  and 

1  S.S.,  1906,  p.  i'<'>.     See  also  Rudolph,  Kriegstechnischt  Zeitschrift,  L907,p.287;  S.S., 

1907,  p.  :;i  i.  -  Vermin  et  Chesneau,  p.  31  I.  3  See  P.  ei  S.,  x\\,  pp.  189,  190. 


396 


EXPLOSIVES 


were  formerly  on  the  Permitted  Li>t.     Monobel,  one  of  the  principal 
had  the  composition  : 

Nitroglycerine  ...-••• 


•  tnium  nitrate 
Wood-meal 
Moisture    . 


78    ii 

- 


To  pass  the  moi  e  Rotherham  test  it  has  been  foimd  necessary  in 

most  cases  to  add  sodium  chloride  or  ammonium  oxalate  : 


Monobel 

-Excellite 

ar- 
kite 

No.  1 

No.  Al 

_ 

\    .  3 

Xitro-glyctrii.' 

10 

" 

5 

12 

Collodion  cotton 

— 

— 

— 

■ — 

Ammonium  nitrate 

68 

i 

" 

shun  nitrate 

— 

— 

_ 

— 

— 

Sodium  nitrafc 

— 

— 

— 

— 

— 

Wood -meal 

10 

— 

— 

— 

— 

Starch 

— 

— 

i 

4-5 

4 

Ammonium  oxalate 

— 

— 

10 

15 

10-5 

— 

Sodium  chloride 

IS 

— 

— 

— 

15 

-ium  chloride 

— 

- 

— 

— 

■ — 

— 

Ammonium  chloride 

— 

— 

— 

3 

— 

— 

Castor  oil 

— 

— 

— 



1 

— 

Mineral  jelly 

— 

— 

— 



— 

•  > 

Limit  charg 

1"  oz. 

28     z. 

10  oz. 

14  oz. 

36  oz. 

-        "Z. 

Power  (swing  of  bal.  pend. 

) 

2  74' 

2-61* 

On  t:  n  list  of  Explosifa  S.G.P.  are  the  following 


Fractorite  D 

Flammivon    III 

carl 

Nitro-grycerine 

4 

4 

Ammonium  nitr 

" 

' 

32 

Potassiimi  nitrate 



— 

1" 

Sodium  nitrate 

1" 

— 

— 

Ammonium  oxa ! 

i 

— 

— 

1     rbohvdrates 

4 

8 

4 

Ammonium  Bulphate 

— 

— 

:  ium  sulphate 

. 

Charge  limite 

V.   uivalent,  Dyn.  No.    1 

420 

191 

AMMONIUM   NITRATE   EXPLOSIVES 


397 


There  is   also   Colinite   antigrisouteuse   B,   which   is   a   gelignite   containing 
ammonium  nitrate  and  other  constituents 


Nitroglycerine     . 
Collodion  cotton. 
Ammonium  nitrate 
Potassium  perchlorate . 
Trinitro-toluene   . 
( iellulose  and  flour 
Magnesium  sulphate 

Charge  Limite 
Equivalent,  Dyn.  No.   1 


25 
1 

20 
6 

12 

29 
7 

800 
460 


Of  German  Grisoutines  the  following  may  be  mentioned: 


. 

Aininon- 

Salit 

Tremonit 

Donarit 

karbonit  I 

Nitro-glycerine  .... 

11-8 



3-8 

4  0 

Dinitro-glycerine 

— 

33  0 

— 



Collodion  cotton 

0-5 

10 

0-2 

0-2 

Ammonium  Nitrate     . 

53-6 

26-5 

80  0 

80-3 

Potassium  nitrate 

— 

— 

— 

5  0 

Dinitro-toluene  .... 

8-5 

— 

— 

— 

Trinitro-toluene .... 

— 

2-5 

120 

— 

Sodium  chloride 

231 

250 

— 

Carbohydrates    .... 

2-5 

120 

40 

4-5 

Coal  dust             .... 

— 

— 

— 

60 

Charge  limite      .... 

660 

730 

130 

300 

Trauzl  test 

287 

268 

4. ".(I 

355 

Astralit 

W 

■lii-i   Astralit 

4 

4 

84-5 

74-5 
10 

7 

7 

1 

1 

1 

1 

2-5 

2-5 

Nitro-glycerine  . 
Ammonium  nitrate 
Sodium  chloride 
Trinitro-toluene. 
Wood-meal 
Charcoal 
Paraffin  oil 

Gelatine-Westfalit  is  a  low-freezing  safety  nitro  glycerine  explosive  containing 
not  more  than  50  per  cent,  diiiitro-chlorliydrine  and  5  per  cent,  nitro-glycerine 
gelatinized  with  a  small  proportion  of  collodion  cotton,  and  containing  ammon- 
ium nitrate,  not  mere  than  LO  per  cent,  saltpetre,  together  with  hydrocarbons, 
vegetable  meal,  neutral  salts  and  nitro-compounds. 


EXPLOSIVES 

In  Austria  an  explosive  called  Pannonit  is  made  : 


Nitroglycerine 



Collodion  cotton 

l-fi 

Ammonium  nitrate 

37 

:  in  . 

4 

Glycerine 



Nifcro-toluene  . 

5 

Alkali  chloride 

2i 

A  little  caput  mortuum    is  added  as  colouring  matter,  and  the  exi 
fired  with  a  special  detonator  containing  trotyl.1    It  replaced  a  former  explo- 
sive consisting  of  ammonium  nitrate,  aniline  hydrochloride  and  sometimes 
ammonium  sulphate.1 

5      1013,  p.  398.  ■  SJS.,    1907,  p.    112. 


INDEX   OE   NAMES 


Abd   Allah   ibn   ai.-Baytiiau,   discovery   of 

saltpetre,  14 
Abd,  Six  F.,  cordite,  304 

deconiiiosition  of  nitro-cellulose,  L92 

gun-cotton,  40 
nitration  of  cotton,  169 
stabilization,  of  gun-cotton,  182 
Adye,  Major,  hand-grenades,  32 

Bacon,  Roger,  discovery  of  gunpowder,  15 
Bebie,  nitration  of  cellulose,  145 

nitro-cellulose  of  high  nitration,  136 

solubility  of  nitro-cellulose,  137 
Bell,  cellulose  sulphates,  151 

nitro-cellulose,  136,  145 
Berl,  nitro-starch,  195 
Berthelot,  investigations,  44,  56 

nitrate  formation,  56 

potassium  chlorate,  377 
Berthollet,  discover  of  chlorate,  35, 
Bevan,  cellulose,  153 

cellulose   sulphuric    esters,    188 
Bichel,  ammonal,  394 

carbonite,  45 
Bickford,  fuse,  38 

Bingham,  R.  W.,  Indian  saltpetre  industry,  57 
Bingham,  viscosities,  337 
Bottger,  gun-cotton,  39 
Bourne,  early  test  for  gunpowder,  27 
Boxer,  Colonel,  rifle  cartridge,  38 
Braconnot.  nitro-starch,  194 
Briggs,  cellulose  sulphuric  esters,   189 
Brown,  E.  A.,  detonation  of  gun-cotton,  41 
Bruley,  nitration  of  cellulose,  137 
Butler,  nitro-starch,  195 

( '  \ni  (  .  cahuecit,  80 
Cellini,  Benvenuto,  gunpowder,  28 
I  hance,  sulphur  recovery,  70 
<  hardonnet,  artificial  silk,  41 


( lhassepot,  rifle,  38 

Chertier,  cellulose  nitrites,  191 

Claus,  sulphur  recovery,  70 

Congreve,  Colonel,  Mar  rocket,  33 

Cooper-Key,  Major,  inspection   of   explosives, 

47 
Crane,  nitro-cellulose  of  low  nitration,  146 
Cross,  cellulose,  153 

cellulose  sulphuric  esters,  188 

Daw,  capped  cartridges,  37 

de  Mosenthal,  structure  of  cotton,  165 

Dcwar,  cordite,  304 

Divers,  decomposition  of  nitro-cellulose,  192 

Divine,  Sprengel  explosives,  43 

Dreyse,  breech-loading  rifle,  38 

Duhem,  Roger  Bacon,  17 

Dupre,  Atlas  powder,  361 

dynamite,  360 

kieselguhr,  358 

potassium  chlorate,  378 

Egg,  J.,  fulminate  cap,  37 

Evelyn,  G.  &  J.,  gunpowder  monopolies,  23,  55 

Evers,  denitration  of  acids,  126 

Farmer,  decomposition  of  nitro-cellulose,  192 
Fave,  Chinese  fireworks,  14 
Favier,  ammonium  nitrate  explosives,  388 
Fernbach,  acetone  from  starch,  347 
Florentin,  progressive  powder,  312 
Forsyth,  detonator  lock,  36 
Frasch,  sulphur  production,  71 
Freeborn,  time  fuse,  38 

Gibbov.  discovery  of  gunpowder,  --2 
Gilbert,  nitrate  consumption.  .~>ii 
Chard,  ammonium  perchlorate,  386 
Griffiths,  Schultze  powder,  48 
Grundlich,  nitrating  centrifugals,  171 


399 


400 


IXDKX    OF    XA.MKS 


C.uttmann.  hall  towers.  Ill 
condensers,  109 
early  manufacture  of,  gunpowder,  19,  24, 

Habkb,  Bynthesis  of  ammonia,  llti 
Haeussermann,  xyloidine,  152 
Bake,  cellulose  sulphates,  LSI,  188 

mtro-cellulose,  136,  14~> 
Hall,  bobbinite, 

dynamite,  363 
Henry,  nitro-isobutyl-glycerine,  _'H 
Hibbert,  freezing-point  of  nitro-glycerin 
Hime,  '  toloneL  <  ireek  fire,  12 

early  projectile-.  30 

discovery  of  gunpowder,  17 

incendiary  missiles, 

rocket-.  :« 
Hofwinner,     ni  tro-isobutj  (-glycerine     nitrite, 

241 
Boitsema,    nitro-cellulose    of    high    nitration, 

1 35 
Hooper,  Indian  saltpetre  industry,  59 
Hoppe-Seylcr,  action  of  bacteria  on  cellulose, 
165 

rch,  195 
Howell,  bobbinite,  90 

dynamite,  363 
Buhner,  mercerized  cotton,  152 
Hutmann,  Fanning,  drilling  machine,  '.'A 
Hyatt,  celluloid,  41 

pyroxylin,  147 

nitratoi,  17'.i 

Jenks,  cellulose  sulphuric  est<  re,  188 

Jentgen,  xyloidine,  152 

Johnson,  D.,  Bmokeless  powder,  18 

Joinville,  wild  fire,  L3 

Joyce,  P.,  fulminate-  cap,  :;~ 

Joyce,  oitro-cellulose  of  low  nitration,  llti 

Kast,  dinitro-chlorhydrin,  _ 

ring-point  of  nitro-glycerine,  2 
Kellner,  cordite,  304 
Kessler,  concentratioD  of  Bulphuric  acid 

■  uer,  acid  egg,  129 
rDar,  wood  distillation,  .'III 

nitro-oxycellulosee,  etc.,  1~>4 
Kneelit.  Labile  cellulose  uitrate,  L51 


Knietsch,  oleum.  97 

Sp.  gr.  of  oleum,  103 
r,  invention  of  rifle 

Labochb,  ammonium  perchlo 

Lawes,  nitrate  consumption,  56 

Leather,  Indian  saltpetre  industry.  .".7.  .59,  GO 
soluhihties  of  saltpetre,  etc..  64 

\.<  faucheux,  capped  cartridges.    ;7 

Lewis,  cellulose  sulphuric  esters,  188 

Lewkowitsch,  glycerine,  203 

Liebig,  fulminates,  37 

Linde,  oxyliquit,  4  i 

Lundholm,  ballistite,  302 

direct  dipping  process,  171 

Lunge,  expansion  of  sulphuric  acid,  L03 
nitration  of  cellulose,    145 
nitro-cellulo.se   of   high   nitration.    136 
solubility  of  nitro-cellulose,     137 
Bpecific  gravity  of  nitric  acid.  117 

MacDokAID,    waste    acid   from   displacement 

pro<  i  las,  L78 
Bdacnab,  water  tamping,  44 
BfcRoberts,  blasting  gelatine,  • 
Majendie,  inspection  of  explosives, 
Manley,  Bpecific  gravity  of  nitric  acid.  117 
Marchlewski,  specific  gravities  of  nitric  acid, 

118 
Marco  Polo,  saltpetre  in  China.  14 
Marcus  Graecus,  fireworks,  17 
II.  A.,  acetone,  345 

specific  gravities  of  mixed  acids,  121 

specific  gravities  of  Bulphuric  acid,   100, 
L03 

volatility  of  uitro-glycerine,  351 
Matthews,  classification  of  celluloses,  L50 
Mercier,  <  aptain,  fua 
Moorsom,  percussion  fuse,  38 
Mukerjee,  Indian  saltpetre  industry,  59,  61 

solubility  of  saltpetre,  etc.,  64 

Nahnskn,    cooling   liquid   for   nitro-glycerine 
nitrator,  218 

Nathan,  CoL  Sir  P.,  cordite,  305 

manufacture  of  gun-cotton,  169 
manufacture    of    artro-grycerine,    -II 
stabilization  of  gun-cotton,  1^-' 

Nauckhoff,  freezing-point  of  nttxo-glyceriii 

Newton.  Chile  nitrate  industry,  62 


INDEX   OF   NAMES 


401 


Nicolardot,  cellulose  nitrites,  191 
Nobel,    A.,    ballistite,    49 

blasting  gelal  ine,  43 

detonator,  41 

dynamite,  3.57 

nitro-glycerine  manufacture,  208 
Nbrrbin,  ammonium  nitrate  explosives,  42 
Nye,  early  test  for  gunpowder.  27 

Ohlsson,  ammonium  nitrate  explosives.  42 
Omelianski,  action  of  bacteria  on  cellulose,  1 1 ..~> 
Ost,  hydro-cellulose,  154 

Paterno,   ballistite,   302 

Pelouze.  gun-cotton,  39 

Perkin.  acetone  from  starch,  348 

Pettit,     mixtures    of    acetone    and    methyl 

alcohol,  346 
Pickering,  specific  gravity  of  sulphuric  acid. 

100 
l'iest.   overbleached   cotton.    158 
Pope,  mercerized  cotton.  152 
Punshon,    nitric-acid    explosive,    4:1 

Reid,  W.  F.,  smokeless  powder,  48 
Reinand  and  Fare.  Chinese  fireworks,  14 
Rintoul,    manufacture   of  nitro-glyeerine.   211 

recovery  of  acetone,  349 
Robertson,  recovery  of  acetone.  349 

stability  of  nitro-eellulose.  188 
Robins,  ballistic  pendulum.  28 
Roewer,  dinitro-chlorhydrin  explosives,  238 
Roscof,  boiling-point  of  nitric  acid.  119 
Roth,  aluminium  explosives,  393 
Rudolph,  ammonal.  393 

Saposhxikoff,  nitration   of   cellulose.    151 

nitro-starch,  190 

specific  gravities  of  mixed  acids,  121 

vapour  pressures  of  mixed  acids.  12.'! 

vapour  pressures  of  nitric  acid.  ll'i 
Sayers,  ballistite,  302 


Schmidt,  carbonite,  45 

Schonbein,  gun-cotton.  39 

Schultze,  .Major,  smokeless  powder,  47 

Schwartz,  Berthold,  discovery  of  fire-arms,  l!i 

Scott,  G.  &  Sons,  distillation  of  glycerine,  205 

Serpek,  aluminium  nitride.   115 

Shaw,  .1..  fulminate,  37 

Shrapnel,  Lieut.,  shell.  31 

Silberrad.  hydrolysis  of  nitro-cellulose.  192 

Snider,  rifle,  38 

Sobrero,  nitro-glycerine,  41 

Sprengel,  explosives,  43,  49 

Stepanow,  solubilities  in  ether-alcohol,  .337 

Street,  cheddite,  380 

Thomson,  Captain  J.  H.,  inspection  of  explo- 
sive-. 47 

Thomson.  J.  M.  manufacture  of  nitro-glycerine, 
211 

Turpin.  picric  acid,  49 
Twitchell.  glycerine,  203 

Uchathjs,  nitro-starch,  1!*7 

Yu.r.vrixEK.  manufacture  of  nitric  acid,  108, 

110 
Veley,  specific  gravities  of  nitric  acid,  117 
Vender,  unfreezable  nitro-glycerine,  239 
Vieille.  nitro-celluloses,  15] 

Poudre  B..  4! I 
Yolkmann.  smokeless  powder,  48 
Vblney,  low-freezing  nitro-glycerine,  238 
Von  Lenk,  nitration  of  cotton,  39.  Iti!i 

stabilization  of  nitro-cellulose.  ls_' 

Wun.EXBERG,  low-freezing  nitro-glycerine,  238 
Weintraub,  effect  of  nitrous  acid.  142 
Whitehorne.  hand-grenades,  32 
Will,  nitro-sugars,  197 

nitro-starch.  195 
Wright,   !•'..   <  ■..  fulminate  cap.  37 


26 


INDEX   or  SUBJECTS 


Acetate  of  lime  340 
Acetone,  340 

manufacture,  340,  :; is 

recovery  of,  349 

tests,  344 
Acids,  manipulation  of,  128 
Adipo-cellulose,  150 
Aerolite,  3!>1 

After-separation,  prevention  of,  *2I  s 
After-separator  for  nitro-glycerine,  21 1 
Ageing  sporting  powder,  325 
Aig  Buppl)  for  uitro-glycerine  manufacl  are,  23 
Ajitx  jiiiwdi  r.  .'is.") 
Alcoholizing   aitro-cellulose,   292 
Aldehydes  in  acetone,  ."i45 
Aldorf'it,  301 
Alkatot,  384 

Aluminium  Explosive,  393 
Amberite,  .'527 

American  gelatine  dynamites,  371 
American  smokeless  powders,  298,  325,  330 
Amines  in  acetone,  .'54.-) 

Ainu ;il.  393 

Ammon-carbonite,  .'S'.ii; 
Ammonia  dynamites,  362 
Ammonite,  389,  390 
Ammonium  nitrate,  388 

explosives,  42,  388 

perchlorate,  385 
Aniline,  272 
Antigel  <lc  surete,  370 
Arabs,  early  fireworks,  1 7 
Arkitc  374 

Aromatic  compounds,  245 
Astralite,  397 
Atlas  powder,  364 
Aus1 1  i.ui  smokeless  powders,  330 
Autoclave  process  for  glycerine,203 
Axite,  308 

Back-flash,  318 


Bacteria,  a<  fcion  of,  on  cellulose,  Ki4 

Ballistite,  49,  301,  322 

Beater  for  oitro-cotton,  187 

Belgian  smokeless  powder,  298 

Bellite,  389,  390 

Benzoates  of  cellulose,  I")-'! 

Benzol,  247 

Bisulphite  process  for  recovery  <>f  acetone,  34  I 

Blank  powder,  334 

Blast  ine,  387 

Blasting  explosives,  357 

Blasting  gelatine,  364,  370 

Blasting  powder,  S7 

first  use,  33 
Blending  gun-cotton.  186 

gunpowder,  84 
Bobbinite,  89 
Boiling  gun-cotton.  182 
Britonite,  376 
Brown  charcoal,  69 

gunpowder,  72 
Bulk  smokeless  powders,  .323 

Cahubctt,  89 

Calcium  carbonate  as  stabilizer,  18G 

( lambrite,  376 

( lannon,  development  of,  29 

( lannonite,  322,  327 

( lapped  carf  ridges,  37 

Carbolic  Acid.  250 

Carbonite,  46,  376 

(  art  ridges,  capped,  37 

Celluloid,  41 

Cellulose,  135,  148 

Acetate,    153 

attach  by  bacteria,  164 
benzoate,  L53 
nitrate,  labile,  LSI 
nil  rales,    lol 

nitrites,  191 
sulphuric  esters,  150 


402 


INDEX    OF    SUBJECTS 


403 


Cellulose,  theory  of  nitration  of,  135 
Centrifugal  nitrating  plant,  170 
Charcoal,  <>7 

brown,  <>!' 

composition  of,  69 

manufacture  of,  67 
Chassepot  rifle,  38 
Cheddite,  4(5.  380 
Chile  nitrate  industry,  62 
Chinese  disc, .very  of  saltpetre,  14 

I  i  reworks,  14 
Chlorate,  discovery  of,  35 

explosives,  377 
Chlorate  of  potassium,  35 
Chloratit,  383 
Coal,  distillation  of,  245 

mine  dangers,  44 

tar,  245,  247 
Collodin,  smokeless  powder,  48 
Collodion  cotton,  147,  180 

washing,  103 
( 'ol  It  lids,  nature  of,  339 
Combined  process  for  glycerine,  203 
Combustible  constituents  of  explosives,  5 
Concentration  of  glycerine,  202 

of  sulphuric  acid,  9(5 
Conveyance  of  nitro-glycerine,  22(i 
Cooling  coils  for  nitro-glycerine  nitrator,    218 
Cop  bottoms,  163 
Cordite,  304 

invention  ,  49 
Cornil,  poudre  blanche,  390 
Corning  gunpowder,  25,  81 
Cornish  powder,  374 
Cotton,  161 

dead,  167 

mercerized,  152,  159 

over- bleached,  158 

preparation  of,  168 

purification  of,  162 

structure  of,  165 

waste,  161 
C.O.V.  (see  also  Sulphuric  acid),  96 
Cut  powders,  84 
Cyanamide,  114 

Daiimknit,  391 
Definition  of  explosion,  1 
Denitration  of  acids.  1 2Q 
Densite,  390 


Detonation,  incomplete,  6 
Detonator  lock,  36 
I  detonators,  .*{<> 
Dinitroacetin,  23!) 
Dinitrobenzene,  266 
Dinitrochlorhydrin,  239 
Dinitroformin,  239 
Dinitro-glyoerine,  238 
Dinitro-glycol,  240 
Dinitro-naphthalene,  269 
Dinitrotoluene,  259 
Diphenylamine,  272 

as  stabilizer,  272 
Direct  dipping  process,  171 
Displacement  process,  174 
Distillation  of  acetone,  344 

glycerine,  204 

nitric  acid,  112 
Donarit,  397 
Dorfit,  391 

Drenchers,  automatic,  for  gunpowder  mills,  79 
Drowning  gun-cotton,  173 

nitro-glycerine,  221 
Drying  cotton,  168 

gunpowder,  83 

nit ro-  cellulose,  289 

smokeless  powder,  307 
Dusting  gunpowder,  83 
Duxite,  374 
Dynamite,  358 

ammonia,  362 

American,  361 

antigrisouteuse,  375 

40  per  cent.,  370 

properties,  359 
Dynammon,  392 
Dynobel,  385 

E.G.  improved  powder,  32(5 

E.C.  powder,  48 

Efficiency  of  propellants,  320 

Egg  for  acids,  129 

Elevator,  automatic,  for  acids,  129 

Endothermic  compounds,  6 

Erosion,  315 

Ether-alcohol,  337 

Explosifs,  N.,  388 

Explosion,  definition  of,  1 

Explosive,  definition  of,  1 

Explosives,  constituents  of,  2 


4<>4 


IXDKX    OF    SUBJEI  TS 


Exudation  of  oitro-glycerine,  369 

F\<  tobies,  design  of,  229 
Farmer's  dynamite,  370 

201 
Faversham  Powder,  390 
Favier  exploeif,  388,  390 
Fermenl  process  for  glycerine,  2<>1 
Filtering  oitro-glycerine,  210 
Filite,  302 
Finishing  gunpowder,  s  1 

trms,  development  of,  28 

invention  of,  18 
Fireworks,  32 

development  of,  32 
Flame,  muzzle,  319 
Flammivore,  396 
Flour.  372, 
Forcite,  372 
Fractorite,  390,  396 
Freezing  of  nitro-glycerine,  232 
French  safety  explosives,  372 

Bmokeless  powders,  328 
Fulmenit,  391 
Fulminates,  discovery,  3<i 
Fume  hoods,  214 
Fumes,  removal  of,  21  \ 
Fuses,  development  of,  38 

safety,  38 

< .  is,  evolution  of,  I 

( relatine  dynamite,  369,  371 

Gelatinized  explosives,  .':i>l 

Gelignite,  369,  :57<» 

German  smokeless  powders,  303,  •'!.'<•> 

Gesteins-Westfalit,  :5(.i:> 

I  (lazing  gunpowder,  83 

Gluckauf,  :{!»] 

( rlycerine,  201 

Granulating  gunpowder  (see  also  Corning),  81 

Granulating  smokeless  powder,  325 

Greek  fire,  12 

I  frenades,  32 

<  rrignon,  340 

Grinding  ingredients  of  gunpowder,  75 

<  rrisounite,  388 
Grisoutine,  15,  395 

<  -i  isoutite,  375 
Guhr,  357 


Gun-cotton,  39,  135,  L68 

discovery .  '■'<'.* 

weighing,  305 
( runpowder,  1 1 .  •_'.'! 

brow  ii.  72 

composition  of,  73 

early  manufacture,  23 

tests.  27 

manufact  ore  of,  73 
products  of  explosion,  90 
Gutters  for  nitro-glycerine,  227 

Hardening  sporting  powder,  '.'>-\ 
Seal  of  liberation,  1 
Hexanil rodiphenj lamine,  27.'> 
High  explosives,  357 
History  of  explosives,  11 
Hydrate  cellulose,  1 53 
Hydrocarbons,  246 
Hydrocellulose,  L53 

[gnttebs,  36 

Incendiary  missile-,  early,  30 

mixt  u  res.  early,  12 
Incorporating  cheddite,  381 

gunpowder,  2 1 

smokeless  powders,  -'.>2.  306 

Indian  salt  petre,    l~> 

I  afernal  machines,  32 
Infusoria]  earth,  357 

Injei  tor  for  glycerine.  208 

Inspection  of  explosives,  !<• 

Japanese  smokeless  powder,  308 

JudSOH    powder,   3l)."5 
K  STONES,  347 

Kieselguhr,  367 

Kinetics  of  nitration,  285 

Kohlencarbonit,  .'57<> 

Kolax,  .*57") 

Kynoch'e  smokeless  powder,  ;>27 

Labybtnths  for  nitro-glycerine  wash-waters, 

215 
Lead  \\  ith  acids,  use  of,  L28 
Ligdyn,  362 

Lignocellulose,  I  19,  150 
Limit  boards,  230 
I. inters,   L63 


INDEX   OF    SUBJECTS 


405 


Low-freezing  nitroglycerine,  2:12 

explosives,  372 
Lyddite,  51,  320 

M.B.  powdeb,  385 
.Melinite  (see  also  Pioric  acid),  49 
DIelting- point  of  oleum,  105 
Mercerized  cotton,  152 
Methyl  alcohol,  341 

in  acetone.  34(> 

Methylamine  in  acetone,  345 

Methyl  ethyl  ketone.  347 
Milling  gunpowder,  70 
Minite,  376 

Minolite  antigrisouteuse,  390 
Mixed  acid,  120 

for  nitrating  cotton,  177 
glycerine,  222 

manipulation  of,  128 
Mixing  acids,  120 

ingredients  of  gunpowder,  7ti, 

nitro-glycerine   explosives,    300 
.Mod. lite.  308 
Monachit,  392 
Monarkite,  39(5 
Monobel,  396 

Moors,  early  use  of  cannon,  19 
Moulding  gun-cotton,  186 
Moulded  powders,  84 
Muzzle  flame,  319 

X  UPHTHALENE,  252 

Negro  powder,  390 
Neonal,  385 
Neu-Westfalit,  391 
Nitrator-separator,  215 

Nitration  of  cellulose,  theory  of,  135 

cotton,  168 

kinetics  of  285 
Nitre  cake,  112 
Nitric  acid,  107 

manufacture  of,  107,  112,  113 

properties,  117 

specific  gravities,  117 

storage,  111 
Nit rie  esters,  5,  194 
Nitro-anilines,  273 
Nitro-aromatic  compounds,  5,  243 
Xitro-benzene,  253 


Nitro-cellulose,  135 

drying  of,  289 

hydrolysis  of,  189 

manufacture  of,  168 

of  high  nitration.  1st) 

of  low  nitration,  14(i 

powders,  289 

products  of  decomposition,  192 

solubility  of,  137 

soluble,  140,  180 

stabilization  of,  182 
Nitro-glycerine,  206 

discovery  of,  41 

high  explosives,  357 
freezing  of,  232 

manufacture,  201  i 

measuring,  306 

powders,  289 

volatility  of,  351 
Nitro-isobutyl-glycerine  nitrate,  240 
Nitro-mcthylanilines,  274 
Nitro-naphthalene,  268 
Nitro-oxy-eellulose,  154 
Nitro-phenols,  277,  281 
Nitro-starch,  194 
Nitro-sugars,  197 
Nitro-toluene,  258 
Nitrous  fumes,  recovery,  111 
Nitro-xylenes,  2(57 
N.O.V.,  96,  97,  103,  131 

manipulation,  131 

03  explosif,  379 
Oleum,  96,  97,  103,  131 

manipulation,  131 
Oxy-cellulose,  154 
Oxygen  carriers,  3 
Oxyliquit,  44 

Pannonit,  398 
Pecto-cellulose,  150 
Perchlorate  explosives,  383,  385 

of  ammonia,  385 

of  potash,  383 
Percussion  caps,  37 
Permanganate  test  for  acetone,  344 
Permonite,  383 
Petroklastit,  89 
Phenol,  250 
Picking  cotton,  168 


i  x  i  >  i :  x  of  subjei  rs 


Picrate  of  amnionic    -  3 

Pic  i 

Picric  a<  2T1 

Poaching  gun-cotton. 

Polarite. 

Poudre  B 

Poudre.  J..  M.,  8 

Pov 

-ing  gunpowoV:.  _ 

smokeless  pon 
Pre-wash  tank  for  nitro-glycerin'  .  2 
Products  of  explosion.  319 
Prog'  •keless  powder.  312 

Promethe.       " 

Propella: 

Pulping  gun-cotton,  185 

Pyrocollodion.  180 

Pyroligneous  acid,  341 

Pyroxylin.  146 

: 

Raschit. 

Recovery  of  nitrous  fumes,  1 1 1 

Rifle,  development  •  t,  28 
invention  of.  _  S 

wder  for.  _  • 
Ripping  ammonal. 
Ri]: 

Roburite.     9  391 

Rockets,  war.  33 
Rottweil  powder,  319 
Roumanian  smokeless  powder,  298 
-ian  smokeless  powder,  298 

S 

*v  explo-: 

-  at  Helen's  powder,  393 
Salit. 

-  tpetre,  13. 

Indian  industr 
manufacture  of,  by  coir 
refining,  61,  65 

•Schultze  smokeless  powder,  47      -' 
itzer's  reagi  at,  153 
veness,  2,  231,  368 
:  ttion  of  nitro-glycerine,  .  I 


for  nitroglycerine.  _ 
Shell, 
carl 

fines,  31,     • 
high  .  31 

shrapnel,  31 

•  L'un  pon 

.     ■ 
rift 
-       pnel  shell.  31 

Smokeless  powder-.  I      17,  288 
cond 

form  of  grain- 
progressive.  312 
rate  of  burning,  310 
.  i'"l 

im  nitrat-  .     _ 
industry  in  Chile.     _ 

Solubihties  of  nitrate  and  chlorides  of  sodium 

and  potassium, 
Solubilities  of  nitro-cellul  ■-•  -.  137 
-  for  nitro-cellul 

•  nt  recov 

oish  Bmokeleaa  powders,  ■  >"l 

ific  gravities  of  mixed  acids,  l_'l 

nitric  acid.  118 

X  O.V.,  106 

sulphuric  acid.  I'd 

ting  powd 

rifle  powders,  308 

rigel  explo^i   •  3,  43, 
:  eter,  88 
Stabil 

ip  mills,  early,  L'4 

•53 
-        ite,  382 
Si 
Straight  dvnaniite,  362 

nic  acid.  2*1 
Sulphur,  69 
Sulphuric  acid. 

concentration,  96 

manipulation  of,  128 

purification,  96 

specific  gravities,  1"1 
Sulphuric  esters  in  nitro-cellulose,  188 
Supercooling  of  nitro-glycerin*: .  _ 
Super-excellite,  396 


Index  of  subjects 


4&1 


Super-kolax,  370 
Swale  powder,  385 

Sua  lite,  374 

Tab,  245 

Teasing  cotton,  168 

Tetralite,  274 

Tetranitraniline,  so-called,  274 

Tetranitro-diglycerine,  240 

Tetranitrophenylmethylnitramine,  276 

Tetranitro-naphthalene,  2<>!t 

Tetryl,  274 

Thunderstorms,  230 

'Tissue  paper,  1(14 

Towers  for  condensing  fumes.  111 

vapours,  349 
Toxicity   of   vapours   of  solvents   used    in   ex- 
plosives industry,  353 
Tremonit,  397 

Trench  mortars,  powder  for,  334 
Trinitro-anisole,  284 
Trinitro- benzene.  258 
Trinitrocresol,  282 
Trinitrocresylates,  283 
Trinitronaphthalene,  209 
Trinitrophenylnitramine,  274 
Trinitrotoluene,  50,  200,  204 

purification,  262 
Trotyl,  50,  200,  264 
Tutol,  375 
Twitchell  process  for  glycerine.  203 

Ose-ijsts  in  nitro-glycerine  houses,  230 


V  \rtiiR  explosions,  352 

Vapour  pressure  of  nitric  acid,  119 

mixed  acid,  122,   123 
Velocity  of  explosion,  <> 
Viscose,  153 

Viscosity  of  solutions  of  nitro-cellulose,  156 
Volatility  of  nitroglycerine,  351 

W  LLSBODE   powder,  327 

War  rocket,  33 

Washing   nitro-cellulose,  169,  171,  173.  177 

nitro-glycerine,  210,  211,  214 
Wash-waters  from  oitro-glycerine,  210 
Waste  acid,  123 

from  displacement  process,  179 

nitro-glycerine  manufacture.   124 
tri-nitro-toluene  manufacture,  201 

Water-soluble  powder,  90 
Water  for  washing  nitro-glycerine,    214 
Weighing  dry  gun-cotton,  305 
Wcstfalite,   389 

Wetter-astral ite,  397 
Wetter-dynammon,  392 
Wetter-fulmenit,  391 
Wild-fire,  13 
Wood  cellulose,  1(14 

distillation  of,  68 

sjiirit  production,  341 
Wrappers,  370 

Xyloidine,  152 

Yonckite,  387 


Eutler  &  Tanner  Frome  and  London 


•' 


